Don’t get a PVC window. They’re mostly junk, poorly designed to sell units at the expense of engineering for wicking moisture. Spend money on a good aluminum clad window. You’ll replace the window once, not very eight years. (Source: I’m a residential architect with 20+ years of specifying windows in a cold and wet climate.)

Also, sounds like what you’re looking for is a replacement/insert style window, where the exterior trim is typically not disturbed to avoid siding replacement/feathering and repainting. This can be a good option, although you will lose a bit of the window glazing size due to the insert frame being attached to the existing opening once the existing window is removed. The problem with inserts though is that while less disruptive to the exterior trim/siding, it doesn’t solve the main problem with cheap windows and construction…namely, the window flashing is bad and not installed properly. No matter what you put in there, you run the risk of being held to the original flashing install for moisture penetration.