Was my first try with vikings, not sure if they can be faster than raynor

I don't think Sgt. Hammer is the fastest hero on any map, assuming perfect execution.

Warhead and BoE should be faster with Zarya, but require very precise management of health and energy. The only map I'm not sure about is Towers of Doom. There are multiple strategies that could be faster than Hammer. Vikings with delicate minion micro on every lane should be faster, also Zarya/Zagara could be faster if executed perfectly. And in my opinion, ARAM maps are less important for speedrunning.

If you want to see what good minion micro looks like with Zag (there is still tons of room for improvement, too): You basically want to preserve the ranged minions as much as you can, by manipulating tower shots and freezing the wave.

EDIT: I just watched the ToD run; You kill the 3rd fort at 3:32. I definitely think it's possible to kill 3 forts faster than that with either Zarya or Vikings. And these Heroes would also allow you to reroute the run, possibly getting the camp after you cap all 3 towers.