Which college is considered more “prestigious” (more academic opportunities, etc.)? What is the social environment like (cliques)? Which would YOU choose?
Amherst. You have the consortium to take advantage if you want. Guys which exist in the working world so good to get used to collaborating with them now, plus the other fringe benefits if that is your preference. 
You’ll get a good education at Wellesley but I’ve heard directly from people that go there that the social life can be a bit dull and the atmosphere is a competitive. Hopefully, you can go to revisits to see first hand what is a better fit for you. Congrats on the great acceptances!