Loadout.tf, for all of its glory, isn't very good at showing the lighting/glow on some eye effects. Nearly everything looks better with a pro ks effect in-game than on loadout. Also, some eye effects are definitely better than others, I'd say Fire Horns and Singularity look good on everything, everything else is somewhere in between, while Hypno-Beam isn't even worth the money (but obviously that's just my opinion).
Here's two examples of why fire horns is the best.