my first Leaders where G1 Optimus and Megatron (Removable fists on Prime and Trigger Crotch Megatron), my first Super Class was Optimal Optimus (BW)
I try to wait until the Leader or bigger get on clearance, since they cost alot nowadays. Scout through Ultra are more affordable
I simply love Leader class toys because they're so sturdy and durable. My first Leader was Animated Megatron because when I was young, the best I could get was the Mega (now, Voyager) size TFs.
Greatest leader of his time? My first in-story leader was an Optimal Optimus (Mega, I think; the pre-Transmetal gorilla one) that I got from a neighbor that was missing every weapon part except the skull mace. My first actual Leader-or-comparable-class figure, on the other hand, was Armada Superbase OP. I'm also proud of the fact that I managed to get one version of each of the Unicron Trilogy leaders; all my OP's are the original colors, but I have Armada Galvatron instead of Armada Megs.
G1 Jetfire ironically lol. He was just about ldr class. He's one of the very few tf I had when I was a youngin...
My first leader was either Movie Brawl or Optimus Prime, can't remember for sure but I'm leaning towards the former.
It's difficult to answer in terms of an equivalent, since like many fans, I've been collecting far longer then there's been a Leader class. Actually, it's a good trivia question in it's own right, as Leader Class didn't exist until Energon, in Armada it was Super-Base (Additionally, Megatron wasn't at that price point), before that it was Supreme (BM-RiD). Supreme has moved up a price point though, so perhaps Super would've been a better past equivalent, despite the lower price point (RiD Optimus Prime and Ultra Magnus, for example, were Supers). So, to truthfully answer the question, my first leader was Energon Megatron. To answer the spirit of the question, G1 Prime I would suppose would be an applicable equivalent.
My first was also G1 Shockwave and G1 Prime and Megatron. I don't Shockwave anymore, but now I have the reissues of Prime and Megatron. Last year, I purchased both 2007 Leaders Prime and Megatron.
I often wonder why there have been so many different size classes when it comes to bigger guys. Anyway, to answer the question, I guess it's Micron Legend Convoy Super Mode
I'm pretty sure the first use of the term "Leader" was in Cybertron, so in that case, Cybertron Leader Optimus Prime.