We're getting away from his original request here, but I agree that Sinistron/Violent Soldier is a great game. It's easy for the first three-and-a-half stages and then suddenly becomes insanely hard, but STILL really fun and you always feel like you've got a chance. Plus, if you want to hear great chip music, this game has some of the best.
While Sinistron is my favorite chip shooter, I think Soldier Blade and Parodius are safer recommendations--SB because it's faster and easier, and Parodius for its sheer entertainment value.
Anyway, I still think Spriggan is the safest bet of any of the games mentioned in this topic. It's got a great power-up system that basically allows you to "make your own weapon," giant bosses, fast and steady action, cool level concepts and graphics, nice music, decent challenge (on the easy side, for sure), and a reasonable price tag. The only way I could see someone disliking it is if they don't like Compile's style in general (and I'm not counting Space Megaforce, as any respectable shooter player hates that slow, drawn-out piece of trash).
The other "major contenders" all have "red flags." Sapphire is extremely expensive and rather short. Sylphia is extremely expensive and quite easy with mostly cruddy level graphics. Nexzr mostly has boring space backdrops and it's fairly tough and uses checkpoints. Macross 2036 is easy and generally appeals a lot more to Macross/Robotech fans than to everyone else. Star Parodier literally put GUTS to sleep.
About thieving the Aero Blasters speed run, I think Thunder Force 2's speed run in its last sidescrolling level preceded AB's by quite some time.
