So I had a request to post the Cicada's I've been driving (which I love so far, and been kicking ass with).
CDA-3C Fast crit machine with ERPPC. Great for getting in some long range shots to open up those criticals, then run in and finish them off close range. Not wise to use this on fresh mechs, look for damaged or no/low armour on.
CDA-3M Dual PPC sniper with ECM. This is my best sniper mech yet, and although it's not a poptart like the blackjack or victor, it does massive damage. My best games have been well over 600 damage and 4kill/7assists. This is also a nice tool to distract with doing hit and runs to help your team.
X-5 3MedL 1LargeL fast and quick punch. Still a hit and run type of gameplay, this one is great for unsuspecting mechs to shoot them in the back with. It stays fairly cool with 1.4 efficiency even on warm maps, so watch it on the hot maps.
I love my medium mechs, but the Cicada really wraps the best of lights with speed and agility, and the firepower and armour of mediums into one mech. Good luck all!