I love me some pullups.
I'm currently at 8 reps with 25lbs around my waist at 160lbs bodyweight. Not great...but getting better.
I dont have a favorite; however, I put the ones that I dislike at the top of my "OH.......your going to beat the crap out of me, okay....lets get it....."
and they are:
1. Squats
2. Dead lifts
I know that feeling, I'll get up and maybe feel a little groggy and think "Oh ****, I have to do squats today!" Then after my first set I'm fired up and ready to go