Have you already checked out the Hip Hop/Open mic/Battle nights in your area? Searching online (youtube) I guess would be your next step. With the internet and home recording equipment you could be working with rappers who live internationally, so don't limit yourself.
rappers are much harder to find then producers, key search words like freestyle rap battle on youtube etc. can help you find some good artist, but it seems like there are much more serious producers then rappers which is too bad.. .
i suggest going to youtube and search upcoming mixtapes. Then filter it by the upload date. This way you can find people who are serious in making mixtapes and they will most likely be good. Message them and try to see if they would like to work with you.
I say stay local. It might not be that they are wack, they just don't appeal to what you do or like. But I would get all local guys and start a movement in my area before I work with rappers I don't know. Let them know what you got going and it could be a great event in your city that becomes bigger than just another mixtape with random rappers on it. I think (IMO) people move to fast and to far away from their surroundings before even leaving graffiti over it for people to see and appreciate. Internet is cool, but YOUR people is 10 times better. Datpiff can either be a place where people just listen to your music.....or experience something much bigger that comes from your city.....show how your city do.
The best way that I've found to connect with "good" rappers is to work with ones that aren't so good and in time if you stay in the mix (and have something that stands out about you) people will start talking about you and the end result is that you'll connect with better ones.