The perfect formula for a "prototypical" leadoff guy is to have a guy who sees a lot of pitches, has good speed on the basepaths so he can steal bases or leg out a hit, and gets on base any way possible. This is the "ideal" lead off guy.
Ricky Henderson and Tim Raines are the protypical leadoff hitters. An OBP of > .350 should be a target, seeing a ton of pitches is good, and power is still important, just less so than at 2-3-4 in the order. Werth right now may be ideal, especially if we bring back ALR or keep at least one of Moore/ Morse.
Also, this is a Morse / Laroche thread, so I'll skip discussion of the rest of the order ideas.