Emby has upset many people in the past, with their move from open source to proprietary. Jellyfin is a fork of emby that is still foss.
I wasn't overly pleased with the seeking either, but I could definitely live with that if subs worked, as the rest was quite nice indeed.
I might give Jellyfin a go at some point. Since they all are children of XBMC, I assume that the metadata format is the same, meaning all my thumbnails, posters, trailers, subtitles and so on can stay in the filesystem next to the media and it'll "just work" with Jellyfin.