I always make sure theres nothing on the brake rotors and i spray thourougly with brake clean when i'm putting it all together.

Not sure about the bearings,

 

Two things come to mind,
1-Make sure you didn't twist the brake hose around as the resulting kink/twist in the hose WILL make it pull (don`t ask how I found that one out).
2- Are the wheel bearings adjusted properly? Too tight prob wouldn't cause a pull but too loose definitely can.
If all that cks out, jack up the front and see if there is any excessive drag, if so crack a bleeder and see if it improves, if so it is prob hose related, if the drag doesn't change any appreciable amount its prob a caliper piston.

 

Try swapping the pads left to right. See if the problem follows the pads.

 

my money is on a bad brake hose or caliper. I went thought the same thing about 6 months ago. All i did was take the calipers apart to relube the slides and it pulled afterward. Mine ended up being a bad hose and caliper.

 

well it was the hoses. I replaced them both and now it stops like a new truck.

the one on the driver side was all brittle and nasty.