For me, it's Motorola. I'm not exactly sure why, but I've been following this brand for years, and still am. My first was a flip-phone, whose model I don't quite recall, and have used it for two years straight. Next, around in 2009, I've gotten myself a Sidekick (don't remember its model, either, sadly). Have had good experience with them both; there's nothing for me to complain about at all, to be honest.
Now, I've got a Motorola Droid Razr, which I've had since 2011, around the time it was first released. I really like its exterior design, personally; it's nice to look at, and also pretty easy to hold onto your hand. It does malfunction every once in a while--such as randomly restarting the system--but those kind of things are bearable, if you ask me. Though, it definitely wasn't like this when I first bought it, so I suppose it's starting to become a little worn.
Have been planning to get it fixed lately, but I'm not sure if I actually, and spend my money on something new. It's going to be latter, most likely, since it would cost only a few extra dollars. Plus, if I do get a new phone, I'd finally have courage to root my current one. Was wanting to do this sort of thing for a long time, but was kind of afraid that I'd mess things up. Of course, there's various ways of fixing, but I'd rather not go through all this trouble; it's currently the only one I frequently find myself using, so I don't want to cause any permanent damage.