I preffered a Mad Cat, but I was pretty damn good with lighter mechs too, playing CTF with an Isis was so damn fun, I had the strange ability to guess when a beam was gonna hit me.
Favourite loadout though was a GaussCat with MRM's (and sometimes LRM's) Infamous Leg Sniper. Pretty much acted like a Gopher, hide behind a hill, rouch down, pop up occasionally to look around and fire off a few shots. I was the bane of Light Mechs, because I could infallibly hit them in their torso with all my Gauss weapons (Think i had 4-6 Gauss weapons on there, I forget.) = bye bye light mech.
Yeah, MadCat's pretty good. I can't get enough of Bushwacker though.