Depends what use it’s for & how heavy a fork you want to run IMO. If you want to keep it light you looking at 32mm stantion, if your not bothered by the weight & want it tough, then 34mm (or 35mm in the case of the pikes).
RS’s SID and Reba’s also should be considered if you want XC & light. For something a bit stiffer there lots of debate between the Rev’s/Fox 32’s, Rev’s seemingly getting a slight upper hand. That said I run some Fox 120’s (came with bike) & they’re hardly noodle like. X fusion’s Slide shouldn’t be over looked as a decent value option (if a little heavy), and no ones screaming about any x fusion horror stories.
If you want something stiffer still, it may well be Pikes can be spacered down to 120mm, and would be the one to go for if you want the current ‘best’, otherwise maybe consider the newer 2014 Fox 34’s (assuming they have sorted the damping out). Otherwise again the X fusion’s Trace look to be a good value option, nice and stiff but maybe not as well behaved once the going get really rough.