My friend is looking at getting a Grand Canyon 29er and the major difference between the ranges appears to be the fork.
Is there a clear winner between the fox terralogic, normal fox and Sid?

Well, I can’t be authoritative on the fork range, but i have a Grand Canyon 7.9, bottom of the range with the “normal” Fox fork – the float 29 evolution CTD (unless the spec has recently changed?).

It’s fine – its a cross country 100mm fork, so it clearly has limits, and i am not a fork fettler (i set it and leave it). I don’t play with the CTD very much now, just tend to leave it in ‘Trail’, like quite a few people probably. I haven’t had any problems with the fork and it rides as you would expect (its tapered and 15mm bolt thru).

Into guesswork-land, I think the Fox terralogic might use the limited travel a bit more effectively and maybe allow you more tuning; I would guess that the SID would be lighter, or your friend might just prefer rockshox?

Cheers
owen