Not much point in comparing the two probably? The set up is different.
UK head of state has zero political input while in USA the role is v political and able to affect stuff.
I used to think ditch the monarchy but now I think. Meh.
Would need to consult the other countries who have Queen as head of state as well or you could end up in a mess where UK ditches monarchy but they are still head of state for other countries etc.
I'm not fussed tbh. Whoever we have will cost £££, could cause division in society (it would be political etc), be vulnerable to all this election interference and whatnot that we've had.
And you'd need to get rid of all the stuff really. The pomp and ceremony that current monarchy does and replace it with something else for £££ cost and that would likely be a bit shit.
It's a wining and dining thingy. It must be dull as fuck tbh. And being polite to whoever you are told to make nice with.
I did like that thing about the Queen, when the Saudi chap came. Driving was banned for women. Bunging him in a range rover and driving him around the place 
Another thing there. If it was a vote thing there'd probably be little chance of a woman doing it? Dunno. Just a thought.