Are you specifically looking for arcade games, Shepardus?
If so, I would agree with most of the choices offered already (with the possible exception of Mahou Daisakusen, the heavy RNG during boss fights is my biggest beef with the game) and add Air Buster, Dangerous Seed, Dragon Spirit, Exzisus, Fantasy Zone, Forgotten Worlds, Gun Hohki, Rabio Lepus and Side Arms (off the top of my head). Hyper Duel's bosses can be rather erratic, everything else fits perfectly, too. Dangerous Seed might look unwieldy but I'd imagine you appreciate the brevity and neat concepts in it. Forgotten Worlds has hectic bosses but you can much more easily plan around that due to the health bar than in something like, say, Mahou Daisakusen.
Gallop and Nostradamus are also fairly close to what you have in mind, those might be a trifle too hard for what you seek, though (that is, if we look at the "not particularly difficult", I smiled when you mentioned freaking Dragon Blaze as an example thereafter
Edit: I should definitely mention Game Tengoku which is like a hybrid between Psikyo (gameplay) and Parodius (visuals, theme, sort-of with the scoring). Not the biggest fan of it myself, you should most likely love it. Difficulty is probably somewhere on the lower end of the Psikyo 1-ALL spectrum.
If you like Caravan games you should also check out the second Macross game (the horizontal one), that is as short as short can be.