The fuel cell is looking a lot more like a non starter. For the huge cost (mainly due to the platinum needed in them) and difficulties with hydrogen production and storage. Very little advancement has been done recently.
I think power cells and batteries have a brighter future.
Yes, the microturbine running a generator is interesting as it delivers pretty good efficiency at max rpm and at altitude. It's also lightweight. And the turbine stage that goes out to a shaft to generate power can also be made a lot more efficient than if you would just take a turboprop type solution - the turbine stage at the end that converts the hot gases to shaft power could for instance be made as a Pelton turbine. Peltons are very efficient at capturing high speed streams and converting it to shaft power.
Or the free piston generator is also a very interesting development, albeit not as light or vibration free as a turbine. But probably a bit more efficient. Basically, it's just an opposed piston running in a tube, but instead of converting the linear motion to a circular motion in a crankshaft that then drives a generator (with all the losses that entails), the pistons themselves act as a magnets and travel back and forth inside a coil (AC current):
Free Piston Power Home
Here's a clip showing a simple free piston generator (ignore the Stirling bit):
YouTube - RESONANT STIRLING ENGINE GENERATOR
Or here:
YouTube - Ubiquitous Electric Power Generation Devices : DigInfo