European release means heel clip style...
And I voted based on that. Now, considering the paddle style, it wouldn't change my vote, but the OP could have been clearer...
Push the button, or push the lever, about the same, except then you think you need to do one, and actually need to do the other. But that is a training issue, not a mechanical one.
back in the early 80s, when I was still interested in playing games, I had a Browning BDA .45 (still have it, too!), which is a Sig Sauer P220, in its original form. Heel type mag release. When Sig changed the mag release to the "American" style (along with a slight recontour of the grip frame), the older design was specifically called the "European".
Yep, playing games with my BDA, I was noticably slower at a mag change than the guys using 1911s. On the other hand, I didn't have to go back and pick up my empty (or partially empty) mags off the ground afterwards.
One of the things I thought about at the time was, how critical would the 1-1.5sec difference in reload speed be, in real life? And balance that against the American style dropping the mag to the ground. I could easily see a real life (ok my fantasy, but bear with me) situation where you are "runnin and gunnin", and NOT be able to go back and get those dropped mags afterwards?
Ok, you get away from the mutant zombie ninja bikers, but you are now down to the one mag left in your pistol, vs having the one loaded mag left in the gunand 3-5 (or whatever) empty mags in your pouch/belt that can be reloaded...assuming that the slightly longer reload time for the European heel release doesn't get you killed, not losing your mags is an advantage.
Of course, in a game, where time counts along with score, European heel release is a disadvantage. But in Real Life?...not so much, I'm thinking.
As to the paddle release, its just a matter of what you get used to. Slightly less likely to be accidently activated. Some people will find them easy and convienient, others won't.
All else being equal (and it almost never is) bigger bullets tend to work better.