Which tool do you need?
Six tools, one studio. They all work on the same picture and hand it to each other, so the question is rarely "which one" — it is "which one first".
Start to finish
Create → Merge → Edit → Expand → Repaint → Enhance → print
That is an example, not a rule. Most projects use two or three, and you will often double back — expand a photo, notice something in the new space you would rather remove, and return to Edit to take it out.
The one fixed point is Enhance. It goes last, because every other tool rebuilds the picture at its own size, so enlarging before you have finished throws the detail away.