I've been running M&M 2e for quite a while with my tabletop group, who are overall easy-going and more concerned with making up novel character concepts than the nitty-gritty details of building. Which works out great because I'm all about the nitty-gritty details of building, and this way I can give advice on my preferred constructions and everyone is happy.
But as always, once you accumulate a large amount of builds, inconsistencies start sneaking in - in this case, related to the use of autofire. Frankly, it's an extra I often like to use because it makes defense more valuable, and it helps compensate for attacks that might be a little undercapped for descriptive reasons - a martial artist who's not allowed to break steel with his bare hands can still lay down the hurt on villains with an Autofire Strike and a high attack bonus.
But if I'm too permissive about it, and I'm also striving for consistency (which I am) it threatens to get out of hand with Autofire effects becoming more common than not. So, which of the following attacks do the good people here on the boards think it's appropriate to build with Autofire?
a) automatic weapons with a high rate of fire.
b) The attacks of a super-speedster like Quicksilver or the Flash.
c) rapid-fire attacks by a skilled energy controller like Starfire or Zuko.
d) The attacks of a fighter with superhuman speed and reflexes, but not "super-speed", like Spider-Man or Deathstroke.
e) The attacks of someone with multiple weapons ("claw/claw/bite", Doctor Octopus, the Hydra) bringing them all to bear on a single opponent.
f) The attacks of someone armed with two weapons and skilled at using them in tandem -"two-weapon fighting".
g) The attacks of a master martial artist with no superpowers, using a "flurry of blows"
Worth mentioning that I've tried to rank them in descending order so that, while I'm not sure where to draw the line exactly, wherever I drew it, I would then not allow autofire for anything further down the list - but of course, there's no requirement that you have to agree with me on that point, especially when it comes to point "h".
Also perhaps worth mentioning that Autofire in 2E was a ranked extra, so I could differentiate by building some attacks as Autofire +2 or even +3. I'm reluctant to do that both because the second and third applications of Autofire seem to me to have diminishing returns, and because it would require rebuilding a lot of Equipment and other common effects, since automatic weapons and super-speed attacks are among the attack forms with the highest "rate of fire", by quite a wide margin. But it might still be the best solution.