[noggin]

Personally I'd love a slightlly more Kodi-friendly version of the PS3 BD Remote - which has a nice mix of Live TV and Media Transport friendly buttons, but is missing Record.  (The Tivo Slide Pro is also a really nice implementation - and the built in QWERTY keyboard inside the slider is amazing at times, but overkill for many I suspect)

For me - an RF remote that had the following functionality would be amazing :

Cursors + Enter
Back
Home
Power (either one key for Kodi device or multiple keys for Kodi, TV, Amp etc.)

Play / Pause (Happy to be combined or separate)
Stop
Record (for PVR)
FF
REW
Next
Previous

Vol+
Vol-
Mute

Channel+ (for PVR)
Channel- (for PVR)
Numeric keypad from 0-9 (both for PVR, and triple-tap alphanumeric text entry for search, config etc.)
Clear (to work with above as a delete key)

Audio (to cycle audio tracks)
Subtitles (to cycle subtitle tracks)
Live TV (to take you instantly to PVR Live TV)
Recorded TV (to take you to your recordings)
Music
Videos/Movies
Photos

Display (to show you metadata)
Info (to show you codec info)

(optional - but useful soft keys)
Red
Green
Blue
Yellow

(Including RF and IR would be amazing - with a way of learning IR or having One4All style magic codes to specific keys, removing them from Kodi)