The best…

Look no further, Infuse is the way to go.
After trying some inferior competition, I switched to Infuse, yearly subscription, to give it a try.
It streams seamlessly ALL formats MP4, MKV, AVI… to ALL my devices, i.e. Apple TV, Chromecast, Samsung TV (directly) from ALL sources, i.e. IPhone, iPad, iMac, NAS, Router memorystick… you name it!
The interface is very userfriendly and I just love their colour scheme.
Highly recommended!