Main Seals - What's the difference?

So I'm looking at all the main seals out there and trying to determine cost v. material v. what works.....

Pegasus: $47 No idea the brand/material
http://ift.tt/1NBcE3a

Oreilly $24 - National made of Fluoroelastomers
http://ift.tt/1NBcE3e

Oreilly $15 - Felpro made of Rubber
http://ift.tt/1NBcDMG

I'm leaning toward the one made from Fluoroelastomers 'cause that's what the Apple Watch Band is made from so it must be good.....

Choices... :(