Garrus is Shepard-lite. A Garrus/Shepard romance is like romancing a mirror.
Well at least Garrus could dance, so that has to be a plus in his column right?
I was a big fan of Liara, but each romance has it highlights. She was the one I picked the majority of the time in Me 1 and Me2. But I'll breirfly state why I liked some of the others, Jack, she was a ******, a bad ass, and took no crap from anyone. There was more to her than that a softer side and vunerable side that brought her to life and made for an interesting character.
Thane as another one that I liked in ME2, even with the dark foreboding of his Karpal syndrome, a man seeking to find peace with himself from his past action with currrent. I Approve.
Tali Tali Tali, I think with me it was more a fascination to see what was under her faceplate, the romance was fun, but it seemed more like the forbidden fruit type, once I had a bite it was okay as romances go never high on my replay list.
Miranda and Jacob, the stories and characters were fine but found the romances just meh.
Garrus, I liked the romance, did not come across as spectacular but it did have some good moments.
Let's not forget Samara our Justicar, although she is not set to the usual romance path you can pursue her (You'll be rewarded in Me3 if you got the citadel dlc) if you are the type that consider a romance culmination with knocking of the boots then this one is not for you, but it is worth following.
Heh let's not forget Kelly......She to ummm sweet, and I found myself mostly romancing her so someone would feed my fish lol.....I think I have blown 100k+ on dead fish replacements.....
Now to ME3
Now here I thought I would remain true to Liara everyone's favorite blue girl. But alas I was mistaken I was totally unprepared and swept off my feet by an upstart new to the series how dare they! By Traynor how dare she! (On ME3 fresh start playthroughs I always found myself gyrating to her much to my utter dismay XD). I just like the personality and way her character comes across.
Coming in just behind our comm officer was Kaiden as m/m it struck another cord in me which I liked, and hey it's Kaider kind sweet and just the right amount of toughness.
Then there is Steve another good romance, only part I didn't like was it seeming like you were taking advantage of him on the rebound, I'd rather have been supportive of his loss than wooing him. He would have come ahead of Kaiden if it was not for that little part.