I would take black's bishop, because when I castle I'm going to be on a black square, and also all the scary stuff that black does to me in the opening seems to always concern the black squares. So it would be best for me to get rid of that bishop if offered that early. But that's me.

I play bg3, if black takes we get the open h file.

bxd6 is a little drawish but fine, e3 is also fine it gives excellent control over e5.

It's like Alekhine's idea against the Colle played in reverse, but it's no big deal for White - like many defenses played in reverse.  Alekhine's plan would be 4 e3, if Bxf4 5 exf4 and White has an overprotected outpost at e5, the half-open e-file, more space, and the doubled f4 pawn not only covers e5 and g5 but could start an attack or pry open the e-file with f4-f5.

Which would be reasonable counterplay for Black, no great shakes for White, but on 4 Bg3 just ...Nf6, ...0-0, and a quick ...c5 and Black is fine.  4 Bxd6 Qxd6 is fine, and ...cxd6 is also a try to imbalance the game further. 

thankyou for your inputs, and I think i may have found something that works because of all the inputs.