1. The SIEGE ENGINE Madcat MkII "E" Variant. The thing is freaking awesome and priced pretty low too. I love the GECM on it.

2. Shadowcat D and E. The D is a freaking hunter due to the BHP and GECM combo paired with the long ranged weaponry. The E is probably my favorite brawler mech. I love the agility of the SCAT in general.
3. New heat system. You actually have to manage heat now, and flamers are scary when you're in a laserboat.
4. Terrain Control is much needed, I love it. I try to get my friends to play, and one of their biggest complaints about previous versions was the lack of objective. I think we could streamline the maps and base locations a bit to allow for better flow of battle though.
5. Heavy Lasers and ATMS. The sound on the HLs is very visceral, kudos on that.