There are many sizes of "startups" too – many Series C and above you'll probably never have to interact with the CEO directly, WLB improves too, but with lower equity and upside
My rule of thumb: if it's big enough to have a dedicated HR person, it's not "really" a startup. Or it's not going to feel like one.
The best size IMHO is ~100-1000 employees. Big enough that you have resources at your disposal, but small enough that you can just pick up a problem and start working it.
