I'm not an expert, but I've done enough reading on the subject to know that there is no "best" system; they don't necessarily have the same goals. FPTP (or plurality system) works if you believe in mandates for parties; PR works better if you believe that having more parties in the government is the best way for accurate representation. Is a large centralized party that has to appeal to many voters going to be closest to the median voter? Or is a bunch of legislators bargaining going to work out best? Should the voters get a direct say in policy making, or do they need mediators? What about regionalism?
All this also depends on whether the voter is rational or not, whether they vote ideologically or strategically, and whether the voter has accurate information or not.
I'll wait until a political scientist writes about this one -- most texts I've read by non-experts are extremely flawed. Like having politicians talk about the internet, really.