So if it was by me with number adjustment on the horse
here would be my idea/number changes (that i think would be what i would like for him not 100% balanced guaranteed)
1st his low base hp
base hp from 625 to 640 - health growth from 106 to 108
2nd
removal of w resistances for some base stats (armor)
Base Armor from 32 to 35
3rd base stat ad increased to encurage him to be able to build trinity force again
AD growth from 3.7 to 4
4th
Q Minnion damage cause i want hecarim to be at least a niece pick toplane
Q Minnion damage from 60% to 66%
with that i think to make him viable lane his q base damage should go up a bit in return nerf the scaling a bit
from 60-180 to 75-195 ad scaling from 90% to 80%
5th idea
make it a bit of a desicion rather if you max w or e second
so here is my idea
W heal from just 25% flat to 20-30% based on w rank (of course as i mentioned no more w armor)
W mana cost to just 55 flat instead of 50-70
W healing cap against non champs from 120-240 to 130-250
Cooldown from 14 flat to 15 flat
E
Movementspeed from 25-65% to (scaling 25%-55/60/65/70/75%) (based on ability rank) (could also be a level scaling if that would be better)
E Base damage (to not just be a tool for spaming q anymore but also to make it the empowered aa better)
Damage from 30-90 (up to 60-180) to 30-130 (up to 60-260) cause well it got nerfed rly insanly fcking hard over the last years
i also think more e base damage would be ok nowerdays because it mainly got butchered so hard cause of the Turbochemtank singery (and well that item doesnt exist anymore)
i still hope he will be a toplaner again someday :/ (or at least viable)