I'm glad you're looking at wood. Plastic doors are far more expensive, not as secure and look horrible
Go for a good solid one. I used hardwood "Alicante" style which is a fairly expensive one as it it has small panels and contains a lot of timber.
Look out for, and avoid, thin glazing bars, or a large panel in the bottom half made of thin ply or MDF whcih a burglar can kick through.
Remember to get a BS deadlock fitted, plus mortice rackbolts top and bottom (you will probably find your insurance co demands that anyway)
If you are likely to want to paint it yourself in future, consider lift-off hinges. They make it far easier and you will not need any skill to re-hang it afterwards.
Take particular care to paint the top and bottom of the door well. These are often neglected as they are awkward and don't show, but this is where damp gets in most.
Hanging a door and fitting locks takes skill (or a lot of time) so I would ask around for a local joiner. It might take him about half a day, or less if you have a modern doorframe in good condition and a standard size. If your old door is rather small, look carefully at any new one and the packing will say how much you can cut off each side - many doors today are veneered or made up, not solid, and can only be reduced by 6mm or so.
Sometimes you will find doors are cheaper at joinery or wood yards than at DIY sheds or Wickes. If you find a local joiner he will (should) know where to go.