I Love to playing with Retroarch but there are some point that i miss hardly.
my most wanted features for next years:
-native 50 Hz PAL support for all systems (could be switchable over quickmenu, pressing a hotkey combi or perfectly should be set automatic if you start a european/brasilian game).
-C64 Core with Auto-Playlist and easy disk-swap possibility in quickmenu
-Amiga Core with Auto-Playlist, WHDLoad
-better/simplier Support for input-things like Driving Devices, Lightguns, Trackballs and Paddle Controllers
-more features to setup a controller ( Analog Stick Adjustments, Callibration, setting Controllerstyle, Hotkey-Mapping for QuickMenu for each Controller individually)
-better Support for unofficiall Controller Adaptors (f.e.: the most common mayflash adaptors for SNES and N64 Pads are not working correctly and simply no other adapter i tried runs without some issue [thanksfully mostly minor issues])
-better integration of MAME2014/2016 (importing some of the cool quickmenu settings from FinalBurnAlpha can do a nice job in some cases i think)
-little more accurate Dreamcast and Saturn emulation
-DOLPHIN