Nine Spades vs. Eight Hearts

J 10 7
A K 10 9
7 4 3
10 9 5
K 9 6 4
J 8 7 4 3
A Q 5 J 10 9 8 6
Q 8 7 6 3 K J 4 2
A Q 8 5 3 2
Q 6 5 2
K 2 Vul: None
A Contract: 5 hearts? 5 spades?

[years later: In coming back to edit the hand, I saw that this first entry on bal vs. unbal had no contract, nor vulnerability showing. Since declarer always has a four bid in either hearts or spades, and the opposition has a good sac in 5 clubs against anything but unfavorable vulnerability, I thought it wouldn't be unrealistic to make this a 5 ht vs. 5 spade hand, where the bal vs unbal factor becomes very important. But I confess that I'm not certain of those factors. In any event, whatever the contract or vulnerability, the important thing is to see that the balanced suit as trump can bring in one more trick than than the unbalanced.]
Played from the North hand, East's most natural lead, the J of diamonds, would wipe out any advantage to the balanced suit as trump. Nor, for that matter, would there be any difference if the ace of diamonds lay with East. But played by South as the cards lie, the defense cannot take more than one diamond and South stands to make one more trick in hearts than he would in spades. So after getting trump out and taking the spade hook, declarer can sluff three diamonds from the North hand (or two diamonds and a club: it doesn't matter since there is only one trump left to ruff diamonds). Winners would be five hearts, five spades and a club, losing a diamond and a spade.
But wait a minute, fella! You've got it all decked out from hindsight with hearts breaking 3-2. Suppose hearts don't break 3-2. Are you sure you'd rather be in hearts? That might depend on who has the 4 hearts, since finessing into the hand without trump should be reasonably safe. Indeed, if I finesse after the second round of trump (when I learn of the bad break), not after the third, I should be reasonably safe even finessing into the hand with 2 trump left. Further, the spade hook might work, if we want to go into suppose this, suppose that! [This was written before I postulated a 5-level contract. If hearts break 4-1, then declarer stands to lose 3 tricks. But all these "what ifs" can carry any hand into la-la land -- away from the point at issue.]
In any event, this is the hand that was, and you can see that in spades, declarer must lose two diamonds and a spade. But in four hearts, declarer gets sluffs on the spades, and loses only a diamond and a spade.

K Q J
A J 8 6
A 8 6
K 10 5
A 8 7 6 4 3
Q 9 7 5
7
Q 7

This hand surfaced recently on OKbridge. My partner opened a club and I bid a spade, and she bid two no trump, and I chanced 3 hearts. I felt certain she would rebid 3 no without four hearts, at which point I would have returned to spades, but a little to my surprise, she bid four hearts, and we were in clover.
Opening lead was a diamond, which I won with the ace, and I now led away from my heart honors. Why did I lead away from the A J instead of maneuvering to take a finesse? Well, for one thing, I'm missing both the king and the 10, so even if the king is onsides, I still could have a heart loser. And the king might not be onsides. Also, I don't have a good quick entry to the closed hand. So I led a low heart, East went up with the king and shot back a diamond, which I ruffed.
Now a heart to the ace (or jack), shows trump breaking 3-2, so I can ruff another diamond, return to dummy by way of a spade, draw the last trump, play dummy's last trump, sluffing my two clubs, and now overtaking the third spade lead from dummy, the closed hand was good.
This depended not just on the cards but on the defense's failure to cash the ace of clubs, in which case it wouldn't matter what suit was trump. Still, as mentioned a number of times, if there is an advantage to one or the other, it will just about always lie with the balanced suit as trump. With that powerful spade suit as trump, I've always gotta lose a trick to the A of clubs (in addition one to the heart K), whether the defense gets around to the suit or not.

Footnote: People sure do get some weird notions. I recall the partner, a pretty fair player at that, who once said the 8-card fit will always do better than the 9-card. That's ridiculous. The first case above won't matter if the ace of diamonds is onsides, and it won't matter if East has four hearts. The second case won't matter if the defense cashes the ace of clubs. Further, these are game-level hands. With weaker hands, I'd any day rather have the 9-card suit as trump. I recall a woman, playing Flannery and with 4 hearts and 4 spades opposite a Flannery opening bid, who insouciantly said, "I thought I'd take the extra trick and bid 2 spades." The "extra trick"? Yeah, once every blue moon, that 4-4 suit works better than the 5-4 as trump because of the sluffing potential inherent in the latter. But there have to be a lot of conditions just right for that to happen. To expect it is optimistic, to presume it, ridiculous. There isn't necessarily an extra trick at any level. Further, with weaker hands, you can lose trump control a lot easier with 8 trump (you've got 3 more than they've got)than with nine (you've got five more than they've got). It isn't 8 vs. nine that's important. It's balanced vs. unbalanced. But keep your eyes peeled.