Define "pretty."
Whatever you say, someone will be bound to disagree with you.
We all have different tastes.
Personally, I am somewhat puzzled by your confession that you don't want to date a pretty girl. Are you saying you don't want a girl who is thought of as conventionally pretty by society, and has therefore become vain and unbearable from all the attention? Or are you saying you have identified in your own mind the type of girl you are personally attracted to, and are now going to deliberately avoid dating your own type?
The first makes sense; the second sounds more like depriving yourself of what you really want.
I don't see anything wrong with having a "type." I don't think it's shallow or superficial to look for someone based on physical criteria as well as personality. The shallow people are the ones who make judgements based solely on physical criteria. A wise person will look for both: their ideal personality and ideal looks. They'll also know that, if there's one of the two which they are willing to compromise on, it should be looks. (Note the word "should." Sadly, hormones take over, and wisdom often flies out the window).
That's just my contribution, based on years of bitter experience of Always Getting It Wrong.
Based on the advice I am giving you, I am not very "wise" (see above). Funny how easy it is to give advice, and how hard it is to follow it.
I always seem to make one of the following mistakes:
1. Date someone I'm incredibly attracted to, so much so, that I don't stop to notice they're a pain in the backside.
2. Date someone I get on incredibly well with, so much so, that I don't stop to remind myself how important it is to have chemistry.
I want BOTH!
Chemistry...and a wonderful Best Friend!
That's what we all should be looking for. You included.
By the way, note that, (to me, at least, as a female) chemistry is FAR more important than looks.
I have dated one or two guys who were drop-dead gorgeous visually (don't ask me how - I nearly fainted) but kissing them was like being assulted by a dead fish or attacked by a bear with rabies. Their attraction greatly diminishes if they don't know how to kiss or have great clumsy hands.
Then I have dated guys who might not have been "conventionally" handsome - but once they kissed me I was like, wow. Putty in their hands.
Therefore, my criteria is not really looks - it's chemistry. Kissing is very important to me.
You can't change the looks you're born with, but it's never too late to work on your kissing style!
I am cautious to generalise about genders too much, for fear of being jumped on - but in general I'd say men are more turned on visually and ladies are more turned on tactilly, and men tend to forget that they have the capacity to become incredibly attractive to females if they take the time to figure out what they really want.
Go think about that for a while! 