I would rate them very similiar.
In the range 20-25 mg Osta, ~50 mg S4 and ~10 mg ACP-105
I find them very low in sides, all of them, when kept in this range.
S4 has the most pronounced sides when dosage increases (vision sides...) but S4 is also the one I have ran the highest as well.
Never went above 25 mg with osta and 15 mg of ACP so I can not say anything about that.
Effect wise is more a question of preference. S4 and ACP give me a more hardening effect and MAYBE a little more strength and Ostarine give me a bit more ease in the joints and sense of wellbeing.
But it’s not a deal breaker in either direction.