Both are nice guns and I would have the same problem making that decision.
I have the P229 and wish I had gotten the Gen II but maybe someday.
One thing I will mention if you are going to shoot the 40S&W and the 357sig make sure you purchase the 40S&W model. Then it is only a matter of changing the barrel for 357sig. The same magazine will work for both.
You cannot buy a smaller caliber gun and make it a larger caliber gun - you have to go from larger to smaller.