Manual transmission swap
there's a lot to unpack here...
the "easiest" swap is all stock. everything fits like it's supposed to, all the parts are out there, there's a FSM to guide you, lots of people have 'em and can answer questions if you get stumped.
however you'll need to go track down all the bits to make that happen... which if you wanna fire up the computer and melt a credit card is an easy button. but if you're not finna drop like $3,000 then it's online classifieds, dealing with CL/offer/MP whack-a-doos, trawling the yards and swaps. and you'll get a used set up together for probably about 2K all said and done.
another option would be a 5spd swap. which, is pretty much the same level of action but add 2+ grand to a new set up from a vendor and probably like 1,500 to piecing together a used setup; then add a level of complication for non stock things and stuffs. but that's a path that's been forged and well traveled, so it's not like you'd be out in the wilderness all alone.
to note, here's a few considerations you may not have thought of: you'll need to cut/modify your floor. which is nbd if you're rolling around in a beater, but if you've got mint interior is kind of a pita. you'll need to modify your exhaust, which if you're not there or haven't tackled that yet is no big whoop, but if you just dropped a grip of dough on headers or pipes you mighten maybe be revisiting all that. if your crank isn't drilled for the 4spd input shaft you'll need to sort that out. and shorten your driveshaft.