As just an A driver I'm not sure how relevant my info is for you, but I feel more comfortable on hards because the drop-off is more gradual. I can push the whole race, whereas on mediums I was tip-toeing around trying not to wear them out and that causes me to be inconsistent. I only did three races and didn't note the times. I was just trying out different possibilities. However my race on hards was by far my best. I had to pit on lap one to put them on since the new practice/qualy/race format caught me out, but all the races had a couple A+ drivers (all on M) in there and the first two races on M I was losing 1-1.5s a lap. With the hards however, I was four seconds behind the leader when I pit to swap the M for H, and I finished 22s behind. Which means I gained about 2s on the A+ rated leader on those seven laps with the hards even though those lead drivers were smashing me by 1.5s in qualy (I think I was putting in high 54s in qualy on M). The last few laps I was watching the timers and I was steadily cutting the gap a tenth or two per sector in the closing laps. I think my best lap on hards was mid-55 whereas the "aliens" were doing mid-54s (in one race I saw a 53-something fastest lap) on M in the beginning but dropping off quickly because of wear.
Like I said, I'm fast but nowhere near alien level, and on top of that I don't practice much, so I'm not sure how relevant all this is but hopefully it at least gives you a general idea of what you're looking at.