I like side snaps mostly since it prevents wing droop. I also like the front snaps that have hip snaps (no wing droop). However I also like elbees since I don't get wing droop even though they are front snapping. I guess I really don't like wing droop.
I like side snaps best. I think it looks better, and you can get a better fit. I think it's more adjustable if you need it tighter around the waist, but looser around the legs. Although I do love my SOS and Mutt's
I used to like side snaps because of the clean look and the ability to adjust the legs separately from the waist. Now though, I am all about front snaps because they are so much faster to snap up, a plus with my wiggly baby. I also find that a single row of snaps accomodates his buddha belly better by letting the diaper curve out and around it rather than trying to go over it.
It is really your baby's shape that makes the most difference, I think. Personal preference a close second.