This was one of those. I enjoyed my Pro-Ject RM5 and Dynavector cartridge. It was my first vinyl rig and it helped me discover that there's more than CD's out there, with cheaper media (if you look for it) and music that I like and sometimes not available in digital. The upgrade decision was easy.
Now I have a Clearaudio Champion with a Clearaudio Satisfy Ebony tonearm and a Benz Micro Ace cartridge. Obviously I can't tell which of these brings the best improvement, but as a whole this thing sounds so much better. I also adjusted the cartridge based on an inner groove radius of 75 mm, vs the 60.2 standard. This is what Clearaudio recommends based on the real angle at which most records are pressed, and I have to say that it makes a noticeable difference (I tried both). Ok; I really have no idea of what I am talking about, but it does make a difference. Sounds smoother, and it just asks you to raise the volume.
This TT has a nice upgrade path, so it will keep me busy the next couple of...years. First in line is their magnetic bearing, which makes the platter literaly float in the air.
I just don't feel like listening to CD's anymore.