There are 900 threads on this board on Supers vs Comps and you won't find a general concensus opinion on the topic.
Damn, I only found 800 of them. Where are those other 100?

But seriously... in all the threads I've seen, arguments are based on what's best for fighters vs. classics (I'm assuming they're referring to 4-ways when they mention classics), and that the Super is the more flexible solution since it can go either 4-way or 8-way. None of these arguments applies for me though when it comes down to players 3 and 4. I did think there'd be some chance for concensus opinion for players 3 and 4 joysticks since those would typically be used for the same style of game--Simpsons, X-Men, NBAJam, etc.
As an FYI to anyone else interested, SlikStik Quad goes for Competitions for all 4 joysticks, although they may have based their decision on price to some extent.
I'd still like to hear from anyone on their decisions/experiences for player 3 and 4 joysticks.