Yep, in the Enstrom the pilot sits on the left, two pax up front, and they can all die together. What a horrible aircraft. Flies like a washing machine.
I've flown on left, right, and center (center in the Bell 47 J as someone noted). Prefer the right, since I can reach for radios with my left hand. If I'm on the left, I have to take my left hand off the collective, put it on the cyclic, (wobble, wobble) and then use my right hand on the radios. Of course, economically it is a bit discouraging since, for example, the JetRanger looks to have enough room for three total up front (a la 500 style) but you'd need to shift the pilot to the left.