Yea, the prusa Mk4 is a great option for you, but honestly even an mk3s kit might be worth looking into. Save a bit of money and you can always buy the upgrade kit to the mk4 later down the line of you deem it necessary.

If you want a printer working straight out of the box and don't care about it being closed source, I cannot recommend the p1p enough. it has been night and day change from my last printer. literally just set it and forget it.

I would definitely steer clear of the ender 3s or other i3 style clones. You spend 95% of your time trying to tune and fix your printer instead of actually using it.

Also, since you don't care about printing anything other than pla, you shouldn't need an enclosure. with any of the mk3s, mk4, p1p, or x1c you are going to be able to print pla and petg perfectly fine with minimal tweaking.