Pittsburgh would win the trade. Mainly because they have another franchise centermen in Malkin who could step up just as good, if not better than Crosby. Washington doesn't have anything close to Ovechkin.
I don't think ovechkin and malkin hate eachother, the capitals and their fans hate the penguins. Ovechkin is just playing hard like he always does and has a big rivalry with both malkin and crosby so he puts a little extra into playing against them.
they are professionals and not a crybaby wide receiver that plays for dallas.
they would play fine together.
now to the question at hand
crosby-semin would be nasty, but i think the trade makes the capitals more of a one line team.
malkin-ovechkin would also be nasty, but i think it also makes the penguins more of a one line team.