I can't say I am keeping trophies per se, but I do have the first dragon I ever tamed, back in 1998, in my stable. I guess I was lucky, because I have never found a better regular dragon. I know that dragons were nerfed at some point...but I don't remember what the nerf was (lower HP maybe?)...but even after the nerf, she is still a 5+ on the pet power calculator, and can stand up to almost anything in the game with me vetting her...including Greater Dragons. Obviously, since she is that old, she has maxed all stats and skills, so she is 7x GM, and has max stats for a regular dragon.
I also have the first jet black nightmare I ever tamed. Again, I guess there was nerf after the fact, because he is a remarkable nightmare...one of the best I have seen.
I am really glad they introduced pet bonding, because without that, I would have lost these two pets years ago.
I just wish I had been smart enough to have tamed an Ancient Wyrm when you still could. That has always been the Holy Grail of taming to me.