I have both and really like the swing tops. haven't had any issues with carbonation yet. when they start looking worn or I get a bad bottle, I'll replace the gaskets. I find them easier on bottling day, because you don't have to mess with a capper. I also like being able to re-seal them and stick the beer back in the fridge between pours if necessary (this is only really applicable to the larger format bottles). also, now that I'm on the road to kegging it'll be a lot easier to grab some swing tops and bottle a few off to bring to a friend's, no capping required.
that having been said, pop tops are essentially free and the caps are cheap, so it's easy to build up a big enough collection to get started. that's what I did, and I've been slowly accumulating swing tops with gift cards, birthday money, etc.