The 3DO and Jaguar were both potential of really great games but unfortunately, both were plagued by lack of titles and just plain bad titles. The 3DO did have some pretty fun games though so I had to vote for the Jaguar.
The 3DO lack of titles? Here's a top 40 list: http://www.retro-sanctuary.com/TOP 40 3do GAMES.html
The 3DO had plenty of games. It was the first platform to many series still going today. It was expensive, that's the only thing that really killed it.
Now the M2 was a complete bust.
I would call the top 4 the lovable losers. And, outside of the first party titles, the N64 had an average game library, at best.