For me it'd depend entirely on the monarchs concerned. Given some of the dodgy 'royals' around the globe, I certainly wouldn't be a royalist in those places.
Having said that, IMHO the Queen has set a very high standard and there's no doubting in my mind that our royal family bring in to UK PLC far more than they take out (in spite of the likes of 'Airmiles Andy' and the various hangers on). It'd just be nice to know that her successor(s) will do an equally impressive job...
My vote is for the monarchy therefore, but based upon current experience rather than blind faith that it's always a good thing.