I've ridden a fairly wide variety of boards, from the average all mountain board, to the flexy park board, to the hardcore back country board.
At one point I had three boards... one for everyday, one for pow days, and a third for thrashing. When I go out, I often ride different parts of the mountain throughout the day. Pow/back country in the morning, park after lunch, and then just bombing the groomers towards the end of the day. I wanted a board to do everything... and I'm pretty sure I've found it!
Since 2006, one of the biggest advancement has been reverse camber, and multi camber shapes. There are many options for boards with these technologies, so the best bet is to go and talk to someone at a shop and get yourself some information about what the technology can do for you.
Personally, I ride a reverse camber board, the Burton Hero. It is characteristically a more park orientated board, but due to the reverse camber shape, it naturally likes to float in powder. It's a 155 length (I'm about 150 lbs), and is easy to spin and can still make hard turns in the trees. Most all mountain boards make some sacrifice, but I really feel like the Hero does everything well. It is the most enjoyable board I have ever ridden. It is the one board that I can ride all day, every day. Whether its dropping cliffs, navigating through trees or spinning off of jumps, it always makes me smile.