My favorite config is the fireknife, though deathrain is my #2. Deathrain is great for long range shooty death against pretty much anything, but especially light vehicles, MCs like the DP or Greater Daemon, and bikers.
Other crisis configs I use or have considered using or are popular:
-Helios (plasma rifle, fusion blaster, and multitracker). Good for anti-TEQ and vehicle but only effective at short range, a critically flawed shortcoming for a crisis suit. Handy for when terminators deepstrike and force you to use short range. I think it was mentioned but it's important to say what it does well. Its short range makes it a little impotent against space marines. I'd take the missile pod that can be fired for 2 or 3 more rounds than the fusion blaster any day against marines.
-Sunstriker (Shas'vre, airbursting fragmentation projector, twin-linked fusion blaster, monat). A single suicidal suit to deepstrike dangerously close to a tank or infantry squad in cover and blow them out. Add shield drones for greater survivability. HW multitracker adds a little extra punch when killing infantry. This configuration can also be used with a flamer instead of the frag projector. Excels at killing light infantry in cover and tanks, but relies on deepstriking to get dangerously close. Best used if you've got a pathfinder unit in your army (for the little extra deepstrike insurance). Fair risk for big reward.
General configuration advice:
-Having a team leader is incredibly worth it because it lets you take a bonding knife (required kit for suit teams since they have so few members and not fantastic Ld). They also let you take a hard-wired drone controller and 2 shield drones. Also required kit IMO.
-2 shield drones are required kit for crisis suits because otherwise, meltas, missiles, or any anti-tank weapon really will take out a 50pt+ model in one shot. Adding 2 shield drones is a 30pt investment that significantly increases the resilience of a 180pt unit. That's 2 extra wounds for anti-infantry fire and 2 invuln saves to throw at anti-tank weaponry. The best part is that if you fail an invuln save all you lose is a 15pt shield drone whose purpose is to die to that stuff anyhow as opposed to if you had shield generators on your crisis suits themselves (thereby making it so you lose your suit if you fail the save).
-Any other kinds of drones are a no-no for crisis suits. They drop the toughness of the squad and you don't get to pick which models (suits or drones) make the saves. If you want to load up on gun drones to make a unit that can pour out str 5 ap 5 shots, take a stealth team. They do it much better.
Hope that helps.