I am still adamant that Joey/Rachel would have worked JUST as well as Ross/Rachel. Their sense of humor, lifestyle, personalities just matched so well. Their love was like Chandler and Monica- sweet, simple and just /right/! Ross and Rachel got all their "heat" from their differences, and that's exciting to watch and gets you rooting for them but differences that extreme can ruin relationships in the long run.
It also would have saved us from the horrible spin-off show!