Currently have Ace and have no major issues with it since I use a good vpn. It sometimes stops on certain channels and I need to switch away from the channel and back again to get it back but I take that as normal for iptv. My only issue is whether there are other providers that will work equally well but have a higher bitrate on the HD and FHD channels. I have a 65" tv and while the picture is certainly not bad on the FHD channels, it does look a bit soft. I also checked the bandwidth being used via my router and it is always in the 3mbps to 6mbps range while watching a FHD. This applied to F1, EPL, and Sky cinema channels.
That might be as good as it gets anyway, I have only ever tried 2 providers and both were pretty much the same but I thought it worth checking. Before someone says it, yes it may never be as good as getting it direct from the major tv companies, I am trying to get the best I can get, whether that is as good or not. It might be that there isn't anything with a higher bitrate and picture quality than ace, in which case that's fine, I already have as good as I can get.
I am only really interested in UK content and am located in the UK (and use a vpn) with main device being a vu+ enigma2 box and secondary device being android phone and tablet. Most watched channels will be Fox (only 720 on ace), comedy central (only 720 on ace), sky cinema, UK sports, discovery and nat geo type channels.
There is no such thing as fhd on iptv no matter what the providers say, the bitrate they stream at it not high enough