DOTM Leader Optimus Prime is my favourite -- he retains some of the nice changes from Buster Optimus Prime (i.e. tanks detach and combine to form the gun) and does away with the cumbersome flip out blades, but for me I really like how they reduced the size of the "ribs" (the two red bits under the windscreen pecs) which was always a more fiddly part of transforming ROTF OP back to truck mode (I often spent more time working on those panels than on transforming the rest of the toy!) But either way, between TF1, ROTF and DOTM we've seen each Leader Optimus Prime toy becoming better than its predecessor. This clearly hasn't been the case w/ AoE.

Looking at images of Generations Leader AOE Optimus Prime and comparing it with First Edition AOE Optimus Prime... I don't know if either one offers a substantial advantage over the other. For each plus that one has over the other, I can see a minus.

I can't tell which toy is inherently better or worse than the other... just take your pick (and maybe go for the cheapest option? )