I have both a raspberry pi bartop and a pc based upright.
I love the classics, and the pi can run those just fine (at least in my non-expert opinion, advanced users may notice errors in emulation).
I have always said though that the pi was a means to an end for me, I have no particular loyalty to it. Looking for a project for my pi was the reason I got into arcade machine building, but I wasn't about to shoot myself in the foot of there was a better option.
For a bartop playing mostly classics, the pi is a good solution, but when I built my upright and had room for a pc, a pc is what I put in there.
Everything was easy to set up, and it runs pretty much everything I'm interested in.
I'm going to give you my standard advice that I give to everyone contemplating a bartop build: consider an upright instead!
It feels so much better than a bartop, and takes up no more room.
A bartop needs a bar to put it on, otherwise you need to put it on some kind of table or stand. When it's on a stand, it has the same footprint as an upright anyway, so why not build an upright.
If you're thinking that a bartop will be easier to move around, you are right to an extent, but a decent sized bartop is still too heavy/unwieldy to be actually portable, and you will probably find that you tend not to move it around much anyway.
My upright is on casters and is actually easier to move around than my bartop.
I bring my bartop to our work Christmas party every year, and it's a real pain to lug the thing around.
Now that I have an upright, I'm going to dismantle my bartop and use the guts to make a 'barstick' so that I have a truly portable machine for parties etc.
Unless you actually have a bar that you want to put it on, the bartop has no real advantage over an upright.