Funny thing, that. I managed to pick up a copy of The Sacred Stones from a local game store for £20 just a few weeks (or months, can't quite remember) before the Ambassador Program was announced. I don't regret the purchase, though; 'cause I'm a pretty big fan of the games, and it was nice to have the physical product, as well. (its just a shame I was pretty late to the Fire Emblem party, considering how many games there are... though most aren't even outside Japan, heh...)
As for a class, I'm not completely swayed in any direction. For a magic-based unit, I suppose I would go with Mage/Sage. I'm pretty big on magic-wielding units, so this would probably be the most fitting role were I to make a character of my own creation. Since there's the trinity of magic, I'd probably opt for preference in Wind, considering from what I recall, a lack of Blizzard, etc. tomes in some of the more recent Fire Emblem games. (I think Shadow Dragon is the only one I've played that had them-- though I'm probably wrong, heh...)
For a mounted class, Pegasus/Falcon Knight would probably be the one I'd opt for. Though with a pretty nasty, but understandable weakness to archery, the mobility of this unit is great for covering a great distance; especially when you need to get to a specific location fast. One good example of this would be in one of the missions in The Sacred Stones, where you need to protect some villagers from mountain spiders. Were it not for having a Pegasus Knight, that mission would have been a pain to deal with, and no doubt would have ended with frustration for lack of being able to protect them. That, and who wouldn't like flying around on an awesome Pegasus!? I had to wait almost a full week to keep playing Shadow Dragon, since for some reason, Elysian Whips were restricted to Online Shop-Only... D=
...and finally, we've got the ground-based, weapon-wielding units. For this, I'd probably go with Myrmidon, since one of the characters I've created in a story that I've been writing is pretty much essentially of that class, were they to be a character from Fire Emblem. Though who doesn't like a nice, swift swordsman/woman with a Killing Edge? Joshua is probably one of my most favoured Myrmidons in Fire Emblem. I kinda have a preference for Swords, as well; not a great lover of axes, and lances would probably be second to a sword in my choice of the trinity.
As an additional note on that though, in the games that have the ability to forge weapons, I like to make unique weapons for certain characters. Kind of adds a hint of uniqueness to them for me; especially for a character of your own creation, like what Shin Monshō no Nazo had and Awakening will have when its released. (I'm really excited for that one!) I just hope that the forging will come with it as well, so that I'm capable of doing that.
But anyway, I'm kinda starting to slip off-topic, now... ^-^;
In summary for those who don't like my pink wall of text, a Mage/Sage is my choice for a magic-wielding unit, Pegasus/Falcon Knight is my choice for a mounted unit, and Myrmidon/Swordmaster is my choice for an infantry-based unit.