This. I usually show Metal Slug 3 or X to people who are new to the NeoGeo. I've found even though they cannot compete with current-gen graphics, peoplefind them appealing because of the fast gameplay and fun action.
Regards.
The Metal Slug games are the ones you'd show people, to show that 2D, low res games can be better than 3D or high res games, if the gameplay is good.
As far as the games with the best graphics to show it off, it would be the Last Blades, Garou, AOF3 and the NGDEVTEAM games like Fast Striker. Or any fighter with large sprites, on a big RGB screen (29"+), like a PVM.
Today's gamers will show no interest to a 24-bit console.
It's like trying to convince them to use a walkman instead of an ipod
Vinyl records are still better than using an ipod (if you use the right equipment- turntable, speakers, etc), even though the technology is much older. Nobody uses Walkmans these days, the sound quality is crap, as analogue tapes degrade over time. And mainstream portable headphones like the Apple earbuds are crap too.