Great decision. I think that EVERYONE should have a neo geo in their collection.
I have two Neo Geo 4 Slots in my garage. One Kiddie short Neo 19 and another V3 "tall boy"
For the kids:
Metal Slug 1
Puzzle Bobble
Blues Journey (kids have discovered this platformer)
Nightmare in the Dartk
For the Adults:
Metal Slug 3
Blazing Star
Mark of the Wolves
Shock Troopers 2
Seems to me that there are like 1/3+ of the games are fighters which I am not that much a fan of. I have friends that love the Neo Fighers so I collected a few for them. I have 6 different Metal Slug games and the first 4 were made by Nasca.
I have mess of other carts but I also think that Neo Bomberman, Crossed Swords, Nam 1975, The Super Spy, League Bowling, Thrash Rally are carts in my own rotation. Pulstar and Last Resort have eluded me for the collectable shooters on the system.