I'm a 1-2 step two foot jumper. Just as you said, I plant my left foot then lead with my right and explode. Terrence Ross and Desmond Mason both jump in this fashion. A lot of two-foot leapers actually go the opposite, planting their right foot first and leading with their left, making their body crook sideways in mid-air (like Vince Carter). Then, as you mentioned, there's the hop step leapers, like Michael Finley. As Burgz mentioned, they all make their own styles work, it just seems to be a matter of repetition and comfort.
Mason, right foot forward example: http://www.youtube.com/watch?v=-ZWaEBMFVRw#t=0m15s
Carter, left foot forward example: http://www.youtube.com/watch?v=4Bra0iEoq70
Finley, hop step example: http://www.youtube.com/watch?v=euBQ7cwpHL8
My trick for my right foot forward explosion off the dribble is to remind myself to stay low and to lead my last dribble in front of my body a little bit (which you can see Mason do in his example). Oftentimes my issue with two foot explosion with a ball vs. without is the fact that the live dribble keeps my body a little too upright at times, especially if my dribble doesn't happen to be incredibly low. As such, placing that last dribble low and in front of me gives me a split second to properly build up my spring and explode.
Through all of this, the good news is if I had to pick between being a one-foot dunker or two-foot dunker, I'd take the one foot, which seems to be your preference as well. I switched over to being strictly a two-foot dunk my senior year in high school and as someone of guard size (6'4'') my only dunk opportunities were fast breaks and needing to plant both feet usually led to slipping, bad plants, or being fouled from behind.
When I switched back to being a primary one-foot guy, dunk opportunities abounded. It's much better to be able to attack and elevate immediately as opposed to worrying about setting one's feet. I still have two-foot dunking in my back pocket and still jump off two very frequently depending on the situation, it's just not my primary means of dunking anymore.