Classic tonearms that I have loved and find hard to let go: Mission 774 (John Bicht version), Syrinx PU2, Linn Ittok, Alphason Xenon, original Rega RB300, Naim ARO.
The arm I use most right now, may well be the best of them all though - it's the Rega RB2000.
Oh, and for some slightly irrational reason I have an SME IV that I've never taken out of the box. It's a beautiful piece of engineering, with a thoroughness and finish that puts it right at the top of the heap. One day I will put it on a mint classic, full acrylic lid, Michell Gyrodec and just look at it...