I have never heard of mrmc or infuse, but aren't they (along with Kodi) essentially just media _players_? And as much as I want to use jellyfin, it's not exactly ready on the platforms I want to use it for (although it's in the works). That leaves Emby, which doesn't have nearly the polish (although I just switched to it and an very happy with it). Not exactly a huge selection of choices...

Kodi is definitely more than a player, it's a full media library. If it doesn't do what you want out of the box (and it mostly does, categorising and metadata etc.), then plugins can handle the rest.

I've tested and used all of these. Emby was a slightly different Plex with several weakneses and some strengths. It was free, now its fremium like Plex. None of the others have native applications for both android and iOS. Infuse is nice if you have an all iOS ecosystem.

update - Kodi has an iOS application if you have a jailbroken an iPhone with iOS 8.