I like Panther, but I am talking early game when enemies are vehicles or under-armored/ poorly maintained mechs, it has the best melee strike of all light mechs and it has 21.5 "free tons" which means enough room for armor and heat sinks. It is slow, but I build it with 3 JJs which gives reasonable evasion.
PPC works well on the early/ short missions, I like its long range (important against base capture/ turret missions), and the +15 Stb.
In this last game I haven't captured a Jenner yet, but in previous, for some reason, I always had poor luck with it; typically it gets sensor locked = half chevrons gone, then missile strike, then alpha strikes, armor gone. My typical mission ended with Jenner needing repairs, sometime serious repair, pilot in the medbay. Worst of all are the convoy ambush missions, which is where I needed the jenner's speed the most
But by far, Firestarter is the most useful light mech; it is so fun, specially on those early assassination missions (and Argos mission), you just keep heat-disabling the big mech while the other 3 take shots at it