As a Mexican, I'm kind of obligated to automatically hate Taco Bell, then again, I've never tried it because I don't have it in my area for obvious reasons.
If I had to pick a favorite, I will always go with Carl's Jr. Frankly, I love the Six Dollar Western.
I've never hated Burger King, but I just never saw anything on the menu that couldn't get anywhere else. There was never anything that just clicked for me. Speaking of which, over the last few years, I've seen the BKs in my area being replaced with Wendy's and I have to admit I prefer that.
As for McDonalds, it's definitely the cheapest chain in my area and it's the only one with a 24 hour drive-thru so its always good for when it's late at night and nothing else is open or when I just feel like not spending too much on a weekend or something. Not too long ago, I ordered a Big Mac combo via drive-thru and they messed up my order. Instead, I got a double Big Mac and a McNifica (that's what they call it here) with large fries and a coke. I had just had a rough night, so I kinda took out my frustration by just eating the whole thing. I didn't regret it, but I'll probably never do it again. I definitely got my money's worth, but I would feel bad if I found out that someone got fired over that.
If there's one fast food chain I wish was in my area, it's Popeye's. I had it for a short while but then it just left. However, a similar thing happened with KFC and now it's back and it's evrywhere. I also like KFC, but I do miss Popeye's.