I used cans, only time I've done FHCs for a long period of time is during my "ugly book" month where I used FHC for the entire month, bar that only the odd FHC to boost happy while doing 25E cans (though swapped to 30E cans recently due to 50% buff in JFA.... thanks mug et al for this
im training right now for raw growth speed. i take 4 fhcs a day. ive heard on the forums thats the best until you hit 1.3b in each stat and then because of cost difference 1.3b-2.6b is best with cans per stat
Also depends on the gym you use like 10E vs 25E vs 50E due to pips etc
FHCs will always be better than cans, they just cost more in terms of x$ per E (It's like $93/95,000 per 1E with FHCs) - but as mentioned above if you have 50% faction + company It can be better though if you're in a situation like me I guess it would be better to stick with FHCs
I believe that around 1.3-1.5b it becomes better to just use SEs for stat per $ but I don't have a calculator for that right now to check