DoomSooth: DragonStrike!
Take my money, NOW!
Used to play this one, back in the day. There was nothing like it. It was good but tough. You also had to make choices now and then. I would advice to get the feather that slows falling...
Catventurer: You can have your dragon shoot out fireballs at things, but I remember this being limited such that you do end up spending most of your time dragon jousting.
00063: I think i'm just gonna stick to Divinity: Dragon Commander for now.
Having finished and enjoyed both, they are completely different games. One is a (land) strategy game with (personal) support from the air, the other is a dragon riding simulator for epic battles in the sky (with some missions being different, as in, fly stealthily, destroy some ships, and so on).
Also, Dragonstrike is tougher, although YMMV. You are expected to handle your dragonlance (tm) and **point it** at your enemies as you charge them, besides using your dragon's breath (the dragonlance is more deadly, but has a limited reach). Your dragon also has talons, and you have a sword that you might use automatically, for some chance short distance side passing. It is not adviced to attack another dragon from below (it will be your flesh against said talons).
Your advantage: You are facing mostly evil dragons and draconians. Dragons have their natural arms, but you are in a team of knight plus dragon. Meaning that you have your dragonlance and your sword. Plus your cause is the good one :) You will be outnumbered in many missions, sometimes you will have team mates, some times you will fly solo. Some mission titles come to mind:
Cavalry,
Pincushion. Nice tough game, possibly with outdated graphics if you care.