I still think the A99 with 70-400G is one of the best telezoom/camera combinations available in terms of IQ. This pairing keeps delivering me crisp, sharp and relatively noise free images even though both are a little tired. I've had the zoom since it was launched and the zoom action is a little sticky, the barrel and hood are scratched and marked and there is a tiny white dust spec inside but it is however pretty free of dust. On the A77 it is good but it's on the full frame that it excels.
There is however a new kid on the block, the Nikon 200-500. It's not an equivalent but perhaps a complimentary long zoom to the decent 80-400 (it's not as good as the Sony 70-400G

). This lens is rather good so much so I bought one and strapped it onto a D7200 (I hear cries of disgust). I'm using this for wildlife and aircraft at the moment.
Anyway see for yourselves.
KLM Embraer 190 with Sony A99/70-400G
Aberdeen choppers with D7200 and 200-500G.
I'm liking the Nikon very much but it won't replace my 70-400G and A99 unless one of them self destructs!
Mike
All my Sony SLT gear gone. Still got my RX100 though.