I love Barney. Probably because his character is like the complete opposite of Neil Patrick Harris in real life. He is a touch but in a comical way and the magic tricks just make it a lot more fun too.
Barney and Robin as a couple make my favorite character. I do like Ted, Lily and Marshall too. It just depends on the episode plot and season for me. There was a time where I was far from a fan of Robin.
Most def. MARSHALL. He's the one guy that every girl wants. At least, that I want. He's extremely nerdy, very dedicated, a family man, and loves his wife unconditionally. AND, HE SINGS EVERYTHING HE DOES! How can you resist a man like that?