As you can see, we all have our own preferences. I prefer 360's interface to ps3's because I find it more functional. I can play recent stuff with just the press of a button by going to the recent menu. Or I can pin favorite stuff like netflix to my pins menu rather than going through ps3's videos menu. Ps3's service is also very slow, one of downsides to being free. For example, when I load up my ps3 friends list, it takes forever to load them all. If I want to look at someone's profile, I have to sync trophies every time, and it takes forever. Even loading up their profile in itself takes effort. Ps3 is slow, slow, slow.
Since this comes down to personal preference, the only preference that should matter is your own. Go to your local game store, ask to try out the same game with both the ps3 and 360, fiddle with the dashboards, the ui, the friends lists, and other features and see which one you prefer.