I used to think MCG was statistically easily the worst HA, in terms of time to kill if all shots hit. Then I measured it to see for myself. I did 10 tests for how long it took to fire a clip, got the average, and divided the clip size by that number to see how many shots fired per second. I then used this and the number of shots to kill with each weapon to get the final TTK. Here's what I measured:
Agile TTK
2.73 HSR
2.34 Beamer
2.32 Repeater
2.01 Mag Scatter
1.61 Suppressor
1.61 Sweeper
1.54 AMP
1.53 Punisher
1.38 Pulsar
1.36 Gauss
1.32 Cycler
1.22 Lasher
1.03 MCG
0.95 Jackhammer (not TripleJack)
Rexo TTK
3.42 HSR
3 Beamer
2.9 Repeater
2.67 Mag Scatter
2.41 Suppressor
2.23 AMP
2.21 Punisher
2.14 Sweeper
1.90 Cycler
1.73 Pulsar
1.71 Lasher
1.7 Gauss
1.49 MCG
1.43 Jackhammer
That combined with the movie (which I can't find) that shows practical TTK with the different HAs. They do MISS in this video, so it's a little more practical representation, but you can't say that it will happen like that in any real situation. Overall, I think MCG is the worst for people with framerate issues, and has the worst chance of hitting once the bloom gets big. So the real issue to me now is bloom, not damage per shot. The bloom is too big too fast, and that's all, aside from performance issues.
My other discoveries from this are that Cycler sucks against rexos, but not agiles, and that Sweeper is not as good as I thought, especially when looking at its clip size. Same for the Mag Scatter. I also discovered that pulsar is VERY GOOD at taking out maxes in comparison to the lasher. The lasher/pulsar do about the same damage per clip to a max and pulsar does it a lot faster. That and the fact that lasher does worse at range and kills about the same speed as pulsar if you hit makes me want to de-cert it over on Markov. (But I can't bear to have a spam-less VS!) One thing I'd like to see is how a punisher + frag grenade does in TTK, I'd bet it's up there with MCG.
Once again, sorry for the long post, but I thought it'd be best to be thorough now.