Another Club Suit

9 8 4
J 9 6 2
Q J 10 6
10 6
Q 10 3 K J 5
K 10 8 3 Q 7 5 4
A 9 5 3 8 7 4 2
9 5 8 7
A 7 6 2
A
K
A K Q J 4 3 2

The first thing to note here is that 5 clubs can be beat on a spade lead. It may be an unlikely lead for the defense to find, and I wouldn't argue against that. Still, any way you slice it and notwithstanding that powerful self-supporting club suit, you can't make game in clubs against best defense while you can in no trump.
And there are a few other factors to consider. A single overtrick will make the hand worth more in no trump than an overtrick in 5 clubs, where indeed, you can't get more than one overtrick, while 3 no offers several avenues to at least one overtrick, with the possibility of three! Indeed, the heart suit is situated such that declarer can himself effect an overtrick even on the seemingly most devasting lead of a low heart. I don't say I'd recommend it, but it's worth noting. [I'm referring to the placement of the J 9 over the 10. Risky to chance when declarer has 9 top tricks in no trump. Just mentioning it, that hearts aren't so open to attack, while you can develop a trick in diamonds if you get a heart opening lead.]
A couple of spade leads could be ducked for a long-card overtrick on the 13th spade. A diamond lead would obviously give you an overtrick in no trump, three overtricks on the ace of diamonds lead (which at least one declarer got in 5 diamonds). Actually it would be best not to duck two spade leads, since a switch to hearts would queer any reasonable hope of an overtrick. You win the second round of spades (if you have assurance that the suit is splitting no worse than 4-2, i.e., the ace of spades is fourth hand) and lay down the king of diamonds.
The defense at worst could then take a third spade and the ace of diamonds, leaving you with 9 winners, which you had from the beginning. But as the cards lie, this would assure you of an overtrick. (However, if the second round of spades comes through your ace, and you don't know that LHO will follow, you might do well to duck one more round. Partners have a way of being upset when you kick away a makable contract.)
Now some people made plus 600 in no trump and the same in 5 clubs. Still, there are a lot of factors saying that three no will play better, as outlined above. Nor is it altogether clear why anyone makes 5 clubs, neither more nor less.
With a spade opening lead, declarer should go down one. Without a spade opening lead, declarer should make an overtrick. Hm-m-m. Hafta look that one up. Well, I did look it up and found: 4 people made exactly 11 tricks in clubs on these plays:
There was one spade opening lead. When that worthy got the lead back with the ace of diamonds, he cashed a spade -- and shifted! The other three got a club opening lead, and it was declarer who kicked away a trick. In one case, he won the opening lead with the 10 of clubs! Well, there goes an entry to the diamonds. In the second case, he properly won the trick with the jack of clubs, played the king of diamonds -- and won the club return with the ace! So much for that valuable 10 of clubs. And in the third case, declarer won the opening lead with the ace of trump, went to the 10 and then led a diamond, just a bit too late. Wait a minute! How come he didn't go down? Hafta look that one up.
Well, it turned out in the remaining 3 cases (with a club opening lead that declarer didn't exploit) that if declarer threw away a chance for an overtrick, all three defenders with the ace of diamonds threw away a chance to beat the contract by ducking the king! And so it goes.