I'm using the RS250 together with an external DAC and headphone amps as a small system for some cans.
Compared to the eversolo, the build quality is a bit better, the display much bigger, you've a (bluetooth) remote and you can also use it as a simple video player.
The HDMI out puts here directly the display data out or/and you can use it (bypassing) for multiple audio formats.
You can put in a SSD, but (through SMB) the transfer rate is very low (better using ftp) and the internal player uses playlists, which I don't like so much.
As stereo Roon endpoint it's very stable, but without Roon, it's a pain to use it (also no DLNA client is implemented).
The eversolo uses a newer android (7.1 <--> 10) and can handle multichannel audio through HDMI (also in using Roon), the internal SSD has much better transfer rates.
But also here the internal audio player is far away from perfect, if you've a larger music collection. Otherwise you can use it a DLNA client.