Mera Peak is in an amazing location, you can see a number of the world's highest peaks from the top (if it's clear), including Everest. IIRC Aconcagua doesn't have quite as much going for it, apart from being slightly higher. Each to their own.

BTW Everest is so steep that it doesn't have a lot of snow on it compared to other high mountains. So it is not even a very attractive mountain (subjective obviously).