Lack of a vertical screen option killed a lot of the Neo-Geo's appeal for me. True, I'm also a Capcom purist over SNK, so I'm not speaking about their fighting games, and a Konami purist over Irem/Nazca, so I'll take Contra over Metal Slug any day. But the landscape-screen Aero Fighters 2 and 3 seriously aren't a patch on the Strikers 1945 games by Psikyo, the original AF developers; and earlier shooters pale in comparison to anything Toaplan ever did.
On the other hand, the faux-Capcom scrolling brawlers are quite fun, and the competitive puzzle games are where the Nooge shines for me.