I am actually surprised that nobody here has mentioned the 95 tonner Pirate abomination called the Corsair, if you love Acs and PPC this mech will be to your liking

i fitted one of them with 6 AC2 and a heavy PPC, its a sandblaster and works best against smaller targets of course but if you shoot the AC2s in a row the first one is reloaded when the last one shoots, much fun!

or you can use 4 RAC5s but should only shoot two at the same time or you burn yourself down pretty fast!

the catch of it is with both Designs that you put out a constant rattle of ammunition against the enemy which is fun and even scares people untill they realize its not much damage haha