I have been comparing the leader effectiveness against other survivors and the truth is he ain't gonna be as good as any other class because he's a damn jack-of-all-trades sort guy. Following this ideology you should never pick only one class.
if you make him a full fighter he will end up being a poor fighter if you compare him with another fighter of the same level. he will be stuck with lower HP and will have less skill in the fighter's weapon (means less accuracy and dmg).
if you make him a full scavenger he will have more HP, similar scavenging skill but won't benefit from the scavenger unique ability to find more items.
if he's to be a full engineer, and please don't ... Never ... do that. he's gonna have similar HP similar trap disarming skill but wound't count as engineer to craft items.
If you make him full Medic he will have more HP and similar healing skills, but that's just it.
A full Recon *might* work, because the leader would have some bright sides such as increased HP (whats a real problem for the recon). Similar speed, similar trap detection skills. but the recon would still be slightly better when using recon weapons.
My Leader distributed his points between fighting and recon.
Edited by Revenant, 06 March 2015 - 11:44 PM.