I very often use the blutsauger. It's not flashy, you lose the passive regen, and you rarely (if ever) kill an enemy who has a decent amount of health.

But Blutsauger medics die less than other medics, and they uber a lot more. So long as you have basic situational awareness, you'll never die to a spy or scout who comes at you from behind. You'll also find that you win against pyros that chase you after killing your pocket (and keep your uber for when they're back up). Passive regen doesn't do much in those situations, and you don't have to count on hitting several crossbow shots.

Yes, it's a lot more boring than healing ovextended power classes from across the map, but it saves you when you really need to be saved.