My main opponents atm are Tau and IG. both players bring quite a few tanks to the battle. The guard player has 3 chemeltas, 3-4 Russes and 1 vendetta most the time. Tau player usually runs 2 Hammerheads, 2 devilfish and 3 Piranhas.
I have less trouble with the Tau player but the Guard seem to eat my lunch (some of it has to do with bad rolls at times)
Anyway, I'm fairly new to SM and this is a list I will try at our next meeting.

Marneus /w Armor of Antilochus

2x Tactical Squad-10 /w Flamer, ML, Powerfist, Rhino
(split them with flamer and sergent in Rhino, ML setup to shoot)

Scout Squad-5 /w heavy bolter and Sergent Telion

Terminator Squad-5 /w Land Raider

Dreadnought /w heavy flamer in Drop Pod

Fast Attack
Land Speeder-1 Multi-Melta

Predator /w TL Lascannon, Side Lascannon


Devastator Squad-5 /w 4 Lascannon

Its alot of anti tank but thats my biggest problem, I can kill the troops with the whirlwind and in assault if needed.