Looking at just outs, the 3/4 suited is way better. The AA only has 7 outs to improve his hand, not that it needs any. The 3/4 has 8 outs for the flush and 6 outs for the straight. Remember that the 5 of spades doesn't help.

Now with that said, I would rather have the AA because I would play to pick up the pot on the flop and take my winnings, instead of trying to milk more. If my opponent wants to make a bad call to chase his draws, then I have to start to try and figure out what he has and hope I hit one of my 7 outs on the turn or 1 of 10 on the river. The only time you should slow play is when you almost have the absolute nuts. If you think there are multiple draws out there, then you need to play aggressively and take the pot as soon as possible to minimize your suckouts.