Unless you use a rotating ballnut then stay away from screws for the reasons Irving shown.
Personally I'd go for the rotating ballnut over R&P anyday but it will work out more expensive and slight more work to impliment than R&P.

I wouldn't go with belts over this length and size of gantry has the tension would need to be high to stop slap and belts will stretch with gantry weight.

R&P will be the easiest to do and if your just cutting wood it will be plenty accurate enough. It will still need larger motors and drives like big ballscrews due to it not being anywhere near efficient has ballscrews so you won't save much in this department.!

My 1st choice would be rotating nut's on 25mm x 10pitch screws.! Could maybe get away with 16mm x10mm but it's a fair old length and 25MM would be stronger. The little difference to performance would be worth it IMO.

NO I CAN'T FAR TOO BUSY.?? . . .But I'm sure there's a little scrout on her that would for the right money.?