Wow, that *could* be one heck of a long list Phil... but off the top of my head...
Most Cessnas are unpressurized SEPs (and both the 172 and the 182 are "default" with FS)
My personal fav, the Jabiru 2, is a "homebuild" that flies beatifully
In similar style, there's the Europa, another homebuild that flies nicely
If you like "interesting" there's the Rutan LongEZ (ee zee) which is a little twitchy but immense fun
My advise, hit AVSim or Mike Stone's website and find yourself some SEPs, give 'em a fly and find one you really like...