Most Medics I know run with the Ubersaw. That’s understandable, it’s a nice weapon. It looks good. It’s useful. It’s balanced. It’s fun to use. And if you see a dumb Spy or an AFK Sniper, you’ve just got yourself free Uber. The Ubersaw also has a fancy kill taunt. A while ago, it used to be silent, so you could hide around corners and catch people unaware with it, just like the Stab Stab Stab taunt.
Some other Medics use the Amputator. When the Medieval Medic set was around, it was a great weapon, but to be fair, no one really used it for the taunt heals. They just used it alongside the everglorious Crusader’s Crossbow to get that lovely regenerating health. These days, it’s about as useful as the Bone Saw.
Lame Medics though use the Vita-Saw. Most Medics seem to agree that the Vita-Saw isn’t exactly balanced, since it rewards Medics who die a lot, and it messes with the eternal question of who has Uber advantage. And it’s got a silly downside.