Sorry, I'm a little late to the party but I've been surprisingly conflicted about this exact thing (I really hadn't put much thought into aspect ratios before and I didn't think I would care this much but anyway!) Since the modern gaming world has almost completely switched from 4:3 to 16:9 ratio (and it seems they will continue with the latter at least for a little while since 4K is 16:9) I really wanted my game to be a little more relevant in that aspect (ratio... pun intended- get it? I'm joking) So after really experimenting with a few different choices here is a great list for your convenience:
https://pacoup.com/2011/06/12/list-of-true-169-resolutions/
I came up with a few stipulations, firstly I wanted the horizontal res to divisible by 48 (because MV is using 48x48 px squares) So I would at least have levels that would fill the "x" space evenly (without falling short) I wasn't really concerned with the "y" axis being exact. I was initially thinking I'd go with the fairly popular 1024x576. However, 1024 / 48 = 21.33333 (so unfortunately, I had to throw that one out) I wanted the screen small however to keep my characters looking big and bold so I didn't want to go over 1024 if I could help it. Next I tried 960x540 which proved to work pretty good as 960 / 48 = 20. This was what I was sticking with for sometime, when in true RPG Maker fashion I realized I needed a "center space" for my specific situation and since 20 is obviously an even number, there is no true center. So, after messing around for awhile longer I came across my sweet spot 1008x567 (yes it is one of the weirdest screen resolutions I've never seen but) it works perfectly for my game as 1008 / 48 = 21 so I can easily make a level with a width of 21 and everything is nice and exact. Fullscreen looks great, even on my giant TV. And I have my precious center so I can put my character perfectly in the middle (for level teleportation reasons, ok jeez??!!)
All in all...
You should ask yourself, "what do I want my screen resolution to do for me?"
Do you want to the level width (or height) to match up exactly?
Do you want your level to have a true center point?
Do you even give a damn?
Anyway, TL : DR (as they say)
1008 x 567 works nearly perfect for me (even though people will most likely look at it and say wtf is that resolution??!!)