I'm looking for PC games where you get to play as a dragon or dragon rider. I've played Divinity II and Dragon Commander, and an old, old title called Drakan: Order of the Flame which really deserves a re-release. And of course, Choice of the Dragon, which gets a lot of attention.
Unfortunately, I can't find a whole lot of others. Does anyone know of any old gems that I've missed?

panzer dragoon had a pc port

Not exactly gems, but there is and [url=http://store.steampowered.com/app/279720/?snr=1_7_15__13]The I of the Dragon.

I don't know if it's the kind of dragon gameplay you're looking for, but the protagonist in the Breath of Fire series can turn into a dragon. They're console games, but the 4th one, at least, also had a PC version.

Wizardry 6-8 have a Dracon race, which gets a breath weapon. That race is also seen in some Japanese Wizardry spin-offs, though I am not sure if there are any that exist for the PC and implement that race. (Apparently, there's a version of Wizardry Empire 2, but I don't know if it has that race.)

Elminage Gothic (and, if you are willing to import and read Japanese, Elminage Original) has a Dragonewt race, which, again, gets a breath weapon.

Might and Magic 8 doesn't let your main character be a dragon, but there are dragons you can recruit, which apparently are overpowered in that game.

Dragon Disciple is available as a kit in the Enhanced Editions of Baldur's Gate 1 & 2 and Icewind Dale.

That's a pretty good-sized list. Thanks very much for all the feedback! I might have to look into some of these.

Well there's a PS2 only sequel to Drakan.
There's also Dragonriders of Pern.. I don't know if you actually get to ride a dragon though and it's pretty awful I think.
Another is an MMO called Dragon's Prophet where you can tame dragons and ride them.
The PS2 title Drakengard also had some segments of dragon riding I believe.
And there was Dragon Strike.
In the Dragonborn expansion for Skyrim you get to ride dragons.

Edit: I can't believe I forgot Dragon's Breath.
And Spyro!
Oh and I found this.

I feel a need to object, The I of the Dragon IS a gem. You get to play as real, flying, fire-spewing, sheep-and-other-critter-eating dragon! What more can you wish for? Maybe only for it to receive some GOG magic and work properly on modern systems - when I last tried it the left/right turning controls sometimes locked up and I could only fly straight, until I came to a complete stop. I remember it being much more fluid. Compared to it, Divinity 2 was kinda disappointing. Nice as a RPG, but the dragon parts were bland, too small part of gameplay and only accessible too late in game (not to mention the expansion). And most of the games mentioned here - MM8, elminage, wizardry - only give you different character portrait, nothing really changes in game mechanics, it doesn't FEEL like playing dragon.

Divinity 2 Ego Draconis

Dragon Strike is a cracking good game. Krynn is a woefully neglected game world.

The Battle for Wesnoth allows you to play as [url=https://wiki.wesnoth.org/Drakes_(race)]Drakes[/url].  
Outside of that, it’s an *excellent* game! Plus, it’s free, so I don’t really know what you’re still waiting for ;)