F/1.2 - 1.4 - 1.8 are compromises. I wouldn't classify them as suck, I only hold the EF 50mm F/1.0 in that category.
I really wouldn't say the 50/1.0 sucks, but it is a highly specialized use lens. If you're not sure you need the 1.0, you're definitely better off with the 1.2. If you're positive you need the 50/1.0, there's an 80% chance you're wrong, and you'd still be better off the the 1.2.
But... if you need to shoot a candle lit dinner in a coal mine, and don't mind (or like/want) the "dreamy" look the 50/1.0 gives, there really is no substitute.
If you need a 50mm F/1, get the leica... Or at least rent one.
If you can afford Leica 50/1, then you can afford all the fast 50s in question here (as a backup or just for fun) .
Really, I believe don't so but point here is the Leica 50mm doesn't suck.
Leica M autofocus sucks and Canon 50/1.0L is just as good optically, if not better.