The NES is boss and shmups are boss so I've concluded that NES shmups must be doubly boss.
I'm a newbie to the genre and only own a few: Dragon Spirit: The New Legend, Sky Shark, and Stinger. I want to get many more because they tend to be fairly cheap and I like NES controls. What games are best, what are the worst, and do any feature hot anime girls?
NES shmups are doubly, triply boss.
Your games are all good, but there's SO much more.
Gradius/Life Force -- The start of a legendary horizontal shmup series -- both games are great.
The Guardian Legend -- If you like a little Zelda-like exploration with your shmups, then you'll love this.
Zanac -- Has the "A.I." system that progressively increases difficulty the more you shoot.
Star Soldier -- Might not have a lot of name recognition, but it did launch a moderately-popular series. Worth a look.
Gun-Nac -- Built on what made Zanac so good, but released very late in the NES lifecycle so it was largely forgotten. Plus, the weapon-shop fast food chick might fit your anime requirement too
Those were probably the popular, well-loved and well known. Check out these shmups too -- NES was definitely not short in this genre:
Hope this helps.
Having to suffer for 100% completion is understood; having to suffer just to finish a game is... well, Sonic Adventure 2.