The only way to prove reliability, with anything, is to shoot the snot out of it and prove to yourself that it is. How else are you going to know? What the gun is doesnt matter either.
Sooner or later too, you will have issues of some sort, at some point. That's just inevitable. If you havent, you just havent shot it enough yet.
As far as the brand loyaty thing goes, I think it depends on experiences more than anything else. Maybe "best luck" loyalty is more appropriate. Ive had great experiences with guns that were supposed to be junk, and terrible experiences with guns that were suposed to be great. The main thing with any of them, individually, regardless of make, is the first line above at the top.
Not really a reliability thing gun wise, but something Ive come to find as, actually, very valuable, is shooting my reloaded brass to failure. Especially the auto brass (revolver brass has its own issues too). The rims get tore up from constant use and that causes all sorts of unexpected failures while you shoot. Its not a gun issue, as the guns normally run fine with factory ammo, or new reloaded brass. Its the well used, worn out brass thats the issue.
The value in that is, you get to practice things you normally wont get to experience, and totally unexpectedly. It teaches you to deal with problems in practice, to the point you dont even think about it, and just remedy it without thought.
As much as we like the positives of what we choose, you do have to learn to deal with the negatives as well, even if you have to make them happen in practice. You just cant ignore them. Or at least if you do so, you do so at your own peril.