I feel as if it's not really even a question for me. Liara and Tali are not so similar that it feels like I'm deciding between two flavors of the same thing.
My primary issue with Liara's romance was that it started too early. Liara became attracted to Shepard very early on. For me, it's a matter of taste - I did not feel that there was enough basis for Liara's romance for me to enjoy it. It's front and center shortly after you meet her, I did not feel like I earned it.
Moreover, I thought Liara was too based around her romance. It felt as if she was created for the purpose of having an (alien) love interest (in other words, she was created for romance). I cannot say for certain if this was the actual intention on Bioware's part, but that was the impression I got.
It was Tali's personality (that I personally preferred to Liara's) and the strength of her romance that made me choose her. So far as the "mystery" aspect that someone mentioned, I do not believe that Tali is a mysterious character and the fact that her face is covered did not factor in (other than her romance's theme of looking past the physical, which I liked).
Edit: I don't believe that Liara abandoned Shepard.
Modifié par Collider, 20 février 2011 - 10:23 .