Springing off of JadeHellbringer and Marwynn, I much prefer the new and improved, sturdier infantry and vehicles. Losing nearly an entire jump platoon in the open to just one, ONE PPC shot didn't make sense to me. My bad for putting them in the open, and I know Battletech isn't supposed to be realistic or anything, but come on! It's not like they train infantry to stand in a straight line for enemy fire.
As for the original thread topic, tonnage or BV, I'll take a 'mech any day. Another thing that hasn't been mentioned is that a 'mech can survive an internal structure section and continue to be tactically effective. A vehicle is well....destroyed.
That's not to say tanks and infantry aren't valuable. Hell, I once had a shutdown phoenix hawk get taken down by three platoons of infantry. They may be grunts, but 'mechs are vulnerable even to infantry when shutdown. Though that's the exception, not the rule.
King of the battlefield? In my humble opinion, that might actually be a 100 ton aerospace fighter loaded to the gills with bombs. That will kill ANYTHING.
But I'd say if you want to call it hype that Battlemechs are the kings of the battlefield, then it's well deserved hype.