First of all they are both great rounds, but to get the max out of ether round you need to reload. Do You?
If not, the 300 wsm will shoot with almost the same speeds that the win mag will, but with a little less recoil.
If you reload, it is cheaper to shoot the 300 win than the 300 wsm. If you reload, brass is better for the win mag and cheaper than it is for the 300 wsm. The 300 win mag has more case capacitive than the 300 wsm. So you can push it faster.
I love shooting my tikka t3 lite 300 wsm it is very accurate and lite to carry.
If you had to choose again I would buy a Win mag, and shoot the 215 gr vld after seeing what Broz has done with them.