Keith Courage certainly isn't horrible, but look what it was competing with at the time for pack in games...Altered Beast! Makes Keith Courage look pretty weak, thats why it has the reputation it does.
If you get a Turbo with some save feature, either a DUO, or a deck with a TurboBooster Plus...Get Gunboat! It's like playing Apocalypse Now, you have this little PBR with a 50 cal, grenade launcher, and front machine guns in Vietnam! Just like the movie. But its very long and you need a Turbo with save feature.
I also like:
-Chase HQ
-Klax
-Devil's Crush
-Sidearms
-Sinistron
-Ninja Spirit...this is the best ninja game ever! blows the socks off of Ninja Gaiden or Legend of Kage, and even Shinobi. This has some of the best music I've heard on the machine and some smooth ass gameplay. It's very hard too, I've not beaten this.