Note that where I give the nod to an Omni, I do so based on a "standard" configuration. I know that Omnis can be modified to individual pilot preferences, but I operate on the theory that Clan supply trains carry large numbers of preconfigured Omni pods, not just loads of loose weapons. Pods can be switched to accommodate differing conditions and situations, but I assume that it isn't nearly as easy to pull a specific weapon out of a pod, reconfiguring the gyro and computers, or even pulling out actuators and rearranging myomers to fit an Ultra AC20 in the slot formerly occupied by an ER Small Laser. Changing a pod, however, could be as simple as bolting it onto the shoulder, plugging in the power cords, and hitting a single button on the configuration keypad to inform the Mech that the left arm has switched from Pod A3 to Pod G11, after which the onboard systems would automatically make the appropriate preprogrammed modifications. Keep that in mind when reading further...
Fire Moth - Harasser and Elemental delivery system. The D is the longtime favorite, even with the flamer, and its speed compensates for its heat. The B carries pulses, allowing it to score more hits from 8 range as it moves at full speed to avoid return fire. The A-Pod is of dubious use, but the ECM is welcome.
Fire Falcon - The B is the smallest I'd take a sniper, and the TC makes up for the speed it has to keep to avoid return fire at medium and long range; I use it to stay at medium for the Clan ERLLs, keeping the enemy's pulses out of range and their big guns in long range (15+). The Primary is lightly armored but is a very well-balanced mech for ground and open-terrain combat.
Locust IIC - Easily replaced by the Fire Falcon Prime for its primary missions, but I include it here because it lacks XL engines and ammunition, which greatly increases its otherwise meager survival chances.
Hankyu - A Hankyu-C is a nasty critter - fast, mobile, with scary guns for such a little mech. Unfortunately, its armor is thin and it's a heatbox, but carefully used, those guns plus that beagle make an effective scout.
Hellion - The Prime is the Hankyu's bigger cousin, with the bonuses of a long-range weapon and cool-running Streaks replacing the Hankyu's extra lasers, with plenty of armor to boot.
Incubus - I don't know why I like this Solaris-looking mech. Its guns are relatively weak, and it devotes more tonnage than I care to waste to MGs. I suppose it's the prospect of those pulses running at 14 under heavy armor protection. The ERPPC variant is powerful but overheated, and the pulses on the standard model and second variant alleviate the running penalty that the Incubus must incur to stay alive.
Cougar - This is another strange choice for me. Its armor is very good for its size, but light mech armor won't protect it from heavy and assault firepower, and it doesn't have the speed to get away or elude lights and mediums. Its value lies in its sniping ability, at which the A, B, and C excel. The C is the most versatile of the three, though it runs hot. The A is well thought out, and the B makes up for the twin-ERPPC overheat failings inherent in the Puma and Nova.
Horned Owl - Survival and pulses; bare-bones construction, no XLs, and decent armor.
Wolfhound - The IIC and Grinner are very good at what they do, and complement the heavy side of a ground-bound light unit well. The IIC is generally better, especially given its low heat, but the Grinner is blessed with a full array of pulses.
Battle Cobra - The A is armored and non-XL, and all those pulses make for a great light-mech hunter or formation guard against harassers and blockade-runners.
Phantom - The C Phantom is frightening, given its good armor, blinding speed, lack of heat, and its uncanny ability to core through the Center Torso Rear of anything that stands still for a round or more.
Pouncer - The A and C are jumping Cougars, while the D is the preferred heavy TC backup for the lighter, non-jumping Phantom.
Grendel - If the Prime didn't overheat so quickly, it would be truly scary, given its max armor, efficient weapons, and long jump.
Ice Ferret - Though the D is overcooled, it's armored, fast, and pulse-armed, and works equally well for hunting smaller mechs and pestering larger ones.
Shadow Cat - All versions are larger Pouncers or jumping Cougars - mobile snipers, basically. The Shadow Cat is distinguished by its higher armor, MASCed speed, and built-in beagle. Whether there is a Clan need for a heavy sniper/scout remains to be seen, however.
Nova - The S configuration combines plenty of heat dissipation with pulse lasers and a beagle to make an excellent attacker/hunter/scout, more than competent in any role except bombardment or sniper. It could lose the MGs, but they could come in handy occasionally.
Black Lanner - I'm not sure this belongs on the Favorites list, but if it does, the C would fit the bill. It offers excellent armor and high ground speed - not to mention MASC - but its guns aren't much heavier than those on the Hankyu-C or Pouncer-D, and its heat is just as high.
Stormcrow - One of the best mechs the Clans have ever produced. Except for the D, all Stormcrows are excellent weapons platforms for a variety of missions. They are all capable of immense destruction, great ground speed, and survival beyond what most mechs can take. The A, C, and Prime are all multirole, multirange mechs, while the B is a deadly close-in fighter, despite its low ammo load.
Vapor Eagle - I don't care what the purists say, this is an effective design that should be accorded more respect. The MGs are of little use, and the heat runs high, but this is the best hunter and harasser the Clans have, bar none.
Glass Spider - The Wolves did a number on their variant, and it's a beast. Full armor with no XLs, fully pulsed-out, sporting a TC, this is one hard monster to kill, and deadly despite its high heat.
Rifleman IIC - See the entry under Glass Spider, but add more armor, jump jets, and plenty of heat sinks. Very few mechs can afford to "draw at high noon" against this overlooked beauty.
Summoner - I don't like Summoners, not at all. They're undergunned and underarmored, but the D almost makes up for that. Its heat is balanced even while jumping; it looks like a Stormcrow-Prime with jump jets.
Black Python - Bite me. Say what you want, there are very few mechs I'd rather have under me in a stand-up fight, and I'll merrily soak the honor gained from winning a battle in a neglected second-line mech against less-capable but more prestigious top-of-the-line Omnis. Lose the MG (and fix the TC!), it's a winner.
Night Gyr - I was waiting for a 4/6/4 heavy, and it's hard to go wrong with a Night Gyr. Massive armor, excellent weapon loads, and ample heat sinks make the A and Prime two very capable multirole mechs, and the D is a fearsome bombardment unit.
Timberwolf - I so very much want to like this, the quintessential Clan mech, but I just can't abide by these awful, wasteful configurations. The A almost fixes this, competing well at all ranges. If the Timberwolf weren't such an all-around good mech, I wouldn't be so disappointed by its misuse.
Warhammer IIC - Joy, joy. A slower, non-jumping Timberwolf-A, without the XLs. Utterly fierce.
Blood Kite - This is something else the Clans need to do, which the Night Gyr started - slow down! They can mount ridiculous amounts of armament if they'd lose the 5/8/0 fixation, and this is a good example. Though it's a heatbox if it fires everything at range, it's a deadly barrage mech, and mobile to boot.
Warhawk - Again, I feel pressured to like this because of popular consent, but I can't bring myself to endorse any except the C and that only by a thin margin. It's hot-running, but the armor is thick and the TC is a killer.
Executioner - The A and D are big, fast jumpers, and all those pulses and heat sinks make me shudder.
Turkina - Again, bite me. Everyone hates the Turkina B, but its effectiveness is undeniable, as is its survivability. The C as well is deadly, especially against RCTs and hordes of smaller mechs.
Bane - The second Bane variant is simple and effective: put as many LRMs on target as possible, sustain the fire rate for an entire battle, and handle the heat. It does these competently enough.
Dire Wolf - I couldn't go without mentioning this one, with good reason. A Dire Wolf-A is low on firepower but is heat-balanced and sustainable. It's a punishing creature, though it needs escort. The S model is a Turkina-C, with even more heat sinks, ammo, guns, and armor. Evil.