You want to be one of the cool kids or go with a known solid game - MM
You want to play the code update game - SW
You want a game with good code and some risk vs reward strategies - ST
MM is a good game but in a small collection I'm afraid it would get old fast. I owned a ST and in a smaller size collection it held up real good as it had several ways to play it and getting to the 2nd or 3rd wizard modes us tough.