I may or may not actually tell you whether you're right, and I may or may not get round to writing more individualized and specific compliments. I do genuinely like all of you though; I don't have anyone on my friends list who isn't there for some reason!
Which of these do you think is the main thing I like about you?
OK, if it's not that, then it might be:
Which would you most want to be liked for (no more than 3)?
If you don't like or want to expand on the options available, comments are open, as ever.