Given my ongoing issues with Rhythmbox, I've just started using Banshee. It seems to tick all the boxes that I require anyway. My use case is music while I work, so I primarily need an unobtrusive player that just sits in the background and responds to hotkeys/multimedia keys (play/pause & next are all I need). Replaygain support is a must for me also.MPRIS2 control via GNOME extension is nice too (
https://extensions.gnome.org/extension/55/media-player-indicator/).
It does have smart playlists, and a cursory look at them indicates that it does what you're looking for.