Wear time on both of these is until I take them off. Seriously. They remove best with eye makeup remover, but I can usually get most off using a cleansing oil followed with a water based cleanser. I can't really tell a difference between the formula of the two, so I guess it boils down to finding colors you like. The Eyeko liners are $15 whereas the stila liners are $20, so that's another factor. The other difference I noticed are in the tops - stila's has this spring loaded thing going on. I managed to launch the top across my bathroom before I figured that out.
Disclosure: I purchased these.