>>21781820on 500 i've had great success with rick dias
you have enough ranged options to cycle through them constantly, only real downtime is when the bazooka is reloading and that's still pretty quick
don't try to play it like the average bazooka -> melee general, its saber animations are slow and melee boost is low. Stun with bazooka, switch to pistols and unload till they get away
On 550 I've had great success with gaplant
It has strong melee, but despite that you can get good results from playing it as a shoot raid which is much more forgiving when you're new. Just be careful of overheating. And keep in mind you have less range than some supports like GP04, so you will still need to play with angles and cover to get the drop on them, which makes for good practice for other raids.