What items and gear should a medic use in raids, if he wants to maximize his healing and utility for the team? I've been using protection wave, healing wave, and healing grenade, but I'm not really convinced this is the best approach.
I think something like this would be the best for team support:
Multi-Boost Beam (trade with Biofeedback Beam if you tend to get shot). Healing Wave Protection Wave Frenzy Wave Healing Morale Boost
If you're the only medic I suggest you use a Nanite healing gun (or even better an Adrenaline gun if you got one). These guns have HoT (heal over time) effects which will slowly heal your friends for 15 seconds after you shot them.
Make sure everyone has active HoT all the time so they regenerate when being shot at. If you're low on Robos or when there are less than two power stations then you might want to use Nanite Regeneration to make sure everyone has enough power to shoot enemies.
If there are two medics then one should use Biofeedback Beam. Left clicking will slowly heal yourself, too. And right clicking your team member is the most powerful healing but also consumes more power.
Also, I never used Multi Boost Beam because its healing per team member is really low and you won't be able to out heal the damage done by bigger mobs, e.g. Guardians.
As for off-hands I usually bring Frenzy, Protection, and Triage Wave.
Look at what other medics are using and if it makes sense then bring something different to complement their abilities.