G1 Ratchet - had the cheap Mexican import with the last 20 years and his arm constantly falls off. Having gotten the custom clip on head on Ebay, I felt a new Ratchet would look better since the old one has yellowed and flaked a lot in the last 20 years.
G1 Snapdragon - one of my first TF's, sadly, his wing hinge had broken. Since I already had all of his accessories, I felt it time for a newer one. Considering he hasn't been reissued, I'm amazed at how well preserved the one I got is. I don't remember my old one being that stiff when he was new out of the box.
G1 Runamuck - bought Runabout not so long ago. The clips on my originals for holding them in car mode did not stand the test of time.
G1 Prowl's rifle - Can't believe it's 7 years since I bought reissue Prowl and got back into collecting. He hasn't lasted well. Surprising considering my TF's aren't really played with. I have TF's that are over 20 years old that have endured significantly better. I've already bought him new door and his rifle snapped.
G1 Galvatron's rifle - Mysteriously disappeared and considering how well i kept most of my 200 TF's from my childhood, mysterious indeed. After 22 years, Galvatron finally has his rifle back. He and Outback were my first TF's. Looking at the rifle and Outback now, I still find it amusing tha Galvatron's rifle is bigger than the Autobot. Me and my brothers first Decepticons were galvatron, Cyclonus and Scourge and the Autobots were all minis and Throttlebots. Boy did they cheer when my brother got Rodimus Prime. Until of course they saw Galvatron tower over him.