If you're only doing 1x1 then it doesn't matter. As for figuring out what sort of RPer you are, read some interest checks from all 3 sections and see which style of writing suits you the best. 

My personal 2 cents tho: quality is all about the group of players you have in your particular RP. The Casual section specifically is a great example. There are Casual Rps that are on the low end (although I wouldn't call them close to Free cause Free is its whole own ball game) and there are Casual RPs that tend toward what you'd consider Advanced. Personally I don't go into the Advanced section much cause even though I have no problem writing at that level, there seems to be a lot of pretentiousness in the Advanced section that you don't get in Casual, even though you can get the same quality. Do with that info what you will, lol.