A monarch needs gravitas, so I won't support any claimant smaller than a mountain range.
Small monarchs accumulate favourites and flatterers.
Discussion
I was always taken with Tolkein's description of a monarch who spent his days fussing over his collection of fine ceramics and serves no other purpose but to occupy the role of sovereign and prevent other, darker forces from assuming it. I'm not sure how that would play out these days now that we have the surveillance state, but Europe seemed to be onto something in the high middle ages, during that brief period between the end of feudalism and the beginnings of humanism.
Ludwig II Wittelsbach is my favourite of that era.
But really, it sucked. Bureaucratic/Military oligarchy with a royal figurehead.
Original-flavour feudalism was better.
Ludwig was very much at the tail end, and possibly even the last gasp of that system. Still, props to the man for his castles and for paying Wagner's bills.