Oh man. Bring that goofball list down to
MG. I'll show ya. Or get pwned and my internet epeen will deflate ever so slightly.
Ok on to answering the question:
At 2500 points, I'd say another warboss on bike. You won't face 1 AV14 vehicle or 1 assault squad, but two or three of each. Possibly more. You'll want the extra killy of a warboss for that
IMO.
I'd definitely take the 675 points of lootas. They really just...hurt.
That leaves about 200 points. More buggies, or maybe a pair of battlewagons for trukk cover cause you'll definitely need it with the kind of shooting you'll face at 2500 points.