There is no perfect eye light, anything that creates light can create an eye light. If it's too bright so that it is filling in too much, then knock it down. Snooting the light, using an egg crate, etc. can only reduce the spill on the other people in the scene, it won't be enough to light the eyes separately from the face. So short of a tiny projected spotlight on each eyeball, any eye light will act as a fill light, so the only trick is to reduce the level. There isn't a magic light that somehow reflects brighter but fills less.
How close the face is to the lens is a factor as well, a small LED on the lens like a Micro LitePanel might be fine if the camera is only three feet or less away but if you are on a long lens and 10 feet away, then it might not be a large enough reflection for you.
On "Smash" I started out using the smallest Lowel Rifa as an eye light but I ended up switching to a 1x1 LitePanel for many shots since it didn't need a power cord run to it, it could run off of a battery, so it was quick to throw it in under the lens on a small stand. Plus if I didn't put a snoot on it, it didn't stick out as far as a Rifa. On Steadicam shots, I'd put the Micro LitePanel on the camera.
Another factor is CONTRAST. The more contrast there is in the color-correction, the more the shadows are pushed darker, the more the fill will drop off... but the reflection in the eye will remain. This is why eye lights are used more / work so well often in movies that are doing some sort of high-contrast effect like skip-bleach.