Personally I kinda like imagining the ponies a bit like pic related. More of a middle ground between the shows artstyle and just straight up horse. We know from EQG that the ponies are supposed to have slightly different anatomy than horses anyway, so this just feels more fitting to me.

I like takes on the ponies that make them look a bit horselike without being completely identical to an irl horse. Picrel I think is a pretty good balance of being realistic while still retaining the stylization in an appealing way. It's closer to how I imagine the ponies would look irl.