I have both, I think Ledger Nano S is the most streamline in consistency
Trezor i Like how I don't have to switch currencies on the hardware device itself.
I haven't tried keepkey, its big, and a bit too simplified,
I know it has Shapeshift, but Shapeshift fees are way too much for me to use anyways.
RE: Ledger Nano S vs. Trezor - Full Comparison