Helbrecht because he gives +1S and rerolls to my Crusaders and LRC.
LRC because its huge volume of shots supports my CC squads very nicely.
Techmarine, repairs the above and more.
Interceptor, mostly ignored (on the board and lists) but it's good at dealing with <fly> and low T on ground thanks to the 2 AC, it's also fairly durable.
Power weapons, cheap and getting buffs like rerolls and +1S makes them pretty good.