Depends on the difficulty. Anything under insanity I like to take Tali and Garrus because I like them as characters and enjoy hearing their banter and want to see them besides my Shepard in the cutscenes.
Insanity though I swap out Garrus for Grunt. Tali and Grunt are a surprisingly effective combo in my experience. I remember her drone getting the attention of a bunch of husks that surrounded it and then Grunt just charged in laughing and punting them. It was pretty cool.
I have to ask about this though:
First of all, my favorite female squad member is: Samara. Why? Because of her cool powers and interesting personality but I really hate when Samara demands Shepard to follow the code without romancing Samara.
Next, my favorite male squad members is Thane Krios because he had very well-concerned personality about his son. He is very attractive but dangerous. I don't like the idea when Thane becomes a assassin. So I decide not to romance him because he is assassin.
When does Samara demand Shepard to follow the code? I've chatted with her many times in multiple playthroughs but never remember her ever demanding I follow a code. Infact she follows Shepard's code due to the oath.
Also what do you mean Thane becomes an assassin? He was already an assassin. Though I guess technically you could say he's "officially" retired in ME2.