If you could experiment with a mode for the first time, would you rather try a new mode like Thor, or an old-school mode like CROWD or Piccolo? I've been thinking about fiddling with FFT and programming, and have thought about bringing some of the original digital modes used by various diplomatic and military organizations back to life. A bit like Hell, but not that old school...
I always get stuck between old and new, I guess that one of the things I like about amateur radio. There's about a 100-year technology range that you can play with in one afternoon!