I like some RTS games, but not all. I prefer ones that focus less on building things and more on (somewhat) effectively using my units. Because of this, my two favorites are Company of Heroes and Dawn of War. I'm also fond of Halo Wars, which is incredibly simple but, in my opinion, more fun because of that. I don't like RTS games in the vein of Age of Empires or Empire Earth. I was able to have some fun with Age of Empires, but overall these types of RTS games just don't click with me.
As for TBS, I love the idea behind them, but I often find it difficult to actually enjoy the games. Granted, I haven't tried very many (Galactic Civilizations II demo and Alpha Centauri being the two major ones), but my experiences with them have been quite similar. My main problem with TBS is that I never feel like I'm playing it right, a problem I don't have with any other genre. I usually start to feel like I'm rushing through everything. This causes me to slow down and obsess over every detail, and then when things don't change, I start to wonder if I'm missing something important. It's annoying because I really want to enjoy TBS, but I just can't get past that feeling that I don't know what I'm doing. That said, I don't foresee giving up on the genre. Every once in a while I'll go back to one of the TBS games that I have, and maybe one day I'll find one that just clicks with me.