Go with the better artist if you guys are making good songs. But sometime the better artist isn't always the most productive one. If at any time you feel like your wasting time end it.
What I saying by doing you is stick with your strengths. If you can make hip hop beats that sound great, roll with it. The same goes for rap beats. But if your trying to force it and you don't like the way anything is coming out, let him/her know. Your going to recognition regardless. The rap artist may have the sound you hear on the radio while the hip hop artist may not. But don't count him out, the game is always changing. As long as your putting your sound/style in it you cant go wrong.
My advise is roll with both, but cut your time in half. One week focus on Hip hop, the next week, rap.