I can't speak for The UE s.f3, But ER6i over Shure.
I started my can quest with them, beautiful sound reproduction. The 3.5 jack isn't very sturdy though, and I was careless getting the wire caught on things.
Eventually the sound went out from losing the connection to the jack.
I "upgraded" to a Shure E4c to my wife's dismay. ($$$) I wasn't blown away by the sound reproduction, but thought they were a solid pair of cans. Loved the thick cable, contra-angled 3.5 plug. After 9 months, the cables were detaching at the ear, started with a small split, then detached completely in 1 1/2 months. Sent them back to Shure, got a new set of SE420's to replace them.
I was excited as hell, new model; expected improvements with the new look, determined to be extra careful with them. Fast-forward to now (8 months later). Wires are covered by glue gun (electrical tape didn't work very well, nor heat shrink tubing). and are cutting out when my head turns.
Ordered a new set of ER6i's last night.