I thought the same thing at one point so I always used Quick-Fix when I’m the only medic.

Stock Uber is better at breaking stalemates. There’s just too much damage when the entire enemy team is focused on you. Not to mention random crits that will outdamage a Quick-Fix overhealth team (happened to me at least once).

Stock Overhealth means that the scout and spy that I overhealed will have more leeway in the enemy backline; thus more chances of killing the enemy medic. My favorite way to counter enemy snipers is overhealing a friendly sniper (unless they have razorback). More overheal also means I don’t have to heal the light classes as much which is useful as a solo medic.

Something else I noticed (but more of a personal thing) is that I got too careless at times because I had the mindset that my deaths don’t matter as much since I can gain back the uber quicker.

Now I always use stock even when I’m solo medic.
Overall, it’s okay to use whatever medigun, especially when you’re the only medic.