I'm going to build one of the RepRap models but I am unsure of which model is best.

What are the main differences between an original Mendel and a Prusa? Is there a quality difference in the end product? Are there any known issues with either version? Thanks.

Edit: Wow, you all gave been great. I've gotten a ton of good info here that I just couldn't find anywhere else. Thanks.

Also, it looks like the consensus is to start with a Prusa. So, I'm off to start sourcing parts.