Surprise answer no. 1: It depends
Given that you
have to give the little buggers guns, a lot of people go for
Option 1: Spinefists, which when combined with no other upgrades at all gives you a 5-point killing machine. Pros: REALLY cheap, actually decent firepower (Hitting on 4's, re-rolling misses, S3
AP 5 actually means a lot when there are 20+ shots). Cons: Short range means you'll only actually fire these once per game probably. Which leads to
Option 2: Devourers. You may get more shots per game with these babies, as they actually outrange the move+assault of most ground based troops, but don't let the "each gaunt gets two shots" fool you. For 160 points you get 32 Spinegaunts; for 161 points you get 23 with Devourers. Mathammer says you get 24 hits from the spinegaunts, and 23 (50% hit, 2 shots each) from the Devourers - at S2, not S3. As I said earlier though, you will - probably - get to shoot the devourers more often in any given game. On the other other hand, the Spinegaunt unit has 9 more warm bodies which is (possibly) 18 more attacks on the charge. Which leads to
Option 3: Fleshborers. Same range as Spinefists, No re-roll to hit, but S4, rerolling Wounds. Tricky. Fleshborer gaunt shooting is a strange beast. On one hand, it is the weapon most likely to actually wound
MEQs. On the other hand, it can do this so well (AP5 aside), that if your shooting goes too well you end up being out of assault range. I like fleshborers, but I'd like them a whole lot more if they were range 18 or AP3 (I can dream, can't I)?
Summary: Avoid Fleshborers unless you can think of an actual use for them (may actually be really useful against T4, 5+ Armour save guys - but how many of those are there?). If you want to shoot more, take Devourers. If you want to smash face, take Spinefists.
All IMCGO, of course. (There's a new saying for the glossary!

)
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