What is its main purpose? As a main source of heating or just to supplement the living room when its chilly?
14kW is massive! Our 8kW i find almost too big, its a bit fuel hungry. Also got a little 4.6 kW which is good. can burn it a bit hotter without it munching through all the wood.
Id go steel. Heats up faster. Most stoves these days seem to have airwash systems to keep the glass clean. But burning hot will keep it clean anyway.
Id go multifuel as coal is nice for the weekends and just keep it going all night too, but this depends if you mainly use central heating?