LHS, easier to lean over collective to look out the door, with door off or no window/bubble window. Someone said being taller it might be easier from the left, however i have had short guys tell me that its easier to lean to the left as they have control of collective and can see further out, whereas leaning to the Right you almost let the collective go to see right around underneath you, when you have short arms...
With your arm on a rest you have total control of the collective when leaning out the left.
Radios aren't too much of a problem, as most guys doing sling work don't need to change radio station too much... but you can always just swap hands to change your radio, hold cyclic with Left hand, change radio with right.
If you fly LHS, then you have spare area in your machine between the seats where the collective used to be, great for placing things etc. Any time that you carry pax, then they cannot mess with the controls as they aren't sitting near to the controls. Also they cannot put anything underneath the collective so that you cannot get it down!!
Flying US built machines, you also use less power to get a load moving as you need to use less pedal when lifting. As you pull up on power, nose goes right, so you just look up and slide forward, you have a great view of what is in front of you, tail rotor bites into fresh air rather than flying from the right, and trying to put in full left pedal to see where you are going. In AS350 not so much of an advantage as the blades turn the wrong way.