Opinion on replacing Minolta AF 100-400 APO.

Use it with A65. It was OK. But there ought to be something better. (Or maybe it's the camera? Or it's me?)

Under $2000 (give or take few bucks...).

No preference - Zoom, prime, a bit longer or shorter, faster or slower, .... Only not too heavy, I'm thru my body-building years.

Your opinions, please. Many thanks in advance.