They are all out there. The Jackrabbit, the Mauler, Fireball, Koshi, Hoplite, Vulcan, and Blackjack name a few. Battlemechs that are considered bottom tier not just for thier weight class, but for all of Battletech. Yet I notice a fair number of fans get drawn to them. Whether it is made famous by their preferred faction, or it uses a weapon system that they are drawn to, or even the mech itself is so rediculously asinine that it has more charm then all the Daishi's and Timber Wolves in the Kerensky Cluster. What is that Mech for you?
for me it is the Jagermech. unequivocally the lowest of the low for many, few would willingly use one, usually being assigned it graced by the RAT with one. I love the thing cause of it's extreme range, low heat and endurance, despite it's low damage output and pitiful armor protection. add on top of that it's look is more fearsome (to me) then it's closest competitor, the rifleman, and it just screams awesome to me.
I took the jagermech and learned how to deploy it, and that has led to a saying with me.
"I never expect you to fear the Jager, but under my hands, you WILL respect it."