I really only use Infuse on the aTV, I bought the iOS apps but I don't actually like them much and see no benefit above Plex, as well as the fact that theres no sync between played on ipad, or played on aTV. I guess I am a Plex nutter, never did "get" the others.
iView, BBC, ITV (would be good) SBS on Demand and Tenplay (just because of Extant) up there with PLex, and I'll be happy. I didnt really like Hulu or HBO, HBO particularly had very little that interested me, and the ads on HUlu annoyed me no end.
Anyway, not long to wait, to find out the rumours were wrong, again.