My Prefence in a fixed wing is the sitting on the LHS for the airmanship aspect (turn right so can see conflicting aircraft all the time as you pass each other etc), its also easier when reaching for your favourite item on the cheeseboard!!
My preference for sitting in a Helicopter is the LHS.
This has nothing to do with which way the main rotors happen to turn but simply the collective lever (up/down!) is always on the left. Apart from the hassle of having to lift ones leg over it when entering/exiting the aircraft it is far more comfortable to sit on the LHS. Unless you are tall or have arms like an orangutan sitting on the right side and watching an external load becomes very uncomfortable very quickly. When sitting on the left you can lean out over the collective and even reference power/pitch by feeling it against your thigh etc. over on the right you are streching your left arm way out to reach and hold the collective whilst straining your neck to the right look out and down at the load/obstacles below.
(Also on the LHS having the Collective on the left guards it from accidental inputs from passengers feet/arms arse or handbag)etc.
Now just to prove the point about aerodynamics and retreating blade stall having no relevence to seating position:
Eurocopter 350 series BA,B2,B3, series pilot sits RHS
Eurocopter 350 B4 series Pilot sits on LHS.
Both machines have identical blades, rotorhead and transmission
both machine blades turn clockwise. not an issue!!
Also
military H500 pilot sits RHS
Civilian H500 pilot sits LHS otherwise identical machine (and rotors) QED
P.S.
Only reason the B4 pilot now sits on LHS is because that was what most pilots have asked for (as well as a twist throttle by the way)
Only reason Military put pilot on RHS in H500 was so when they progressed to the huey they were used to sitting on the RHS.