I always found Garrus to be my friend, rather than a lover. In fact, in my first play-through of the ME series with FemShep, I didn't romance anyone at all. I knew who was available, but I felt like being friends with them all. My next play-through will be with a male Shepard. I would romance Kaiden the entire way through, but you can only do that in ME3.
Maybe Ashley? But then, I'm killing her off this time. The only annoying thing with the romances in this game is that because many companions don't stay companions (becoming guest appearances in some of the games) I'm worried that you won't get a complete experience, and it may come across as slightly stunted.
Oh! Tali! She's with you the entire length of the game. Got it. I'll romance Tali across all the games. You can't romance Tali in ME1, but she's with you all the way anyway.