My ex was there when the Ospreys left Loch Garten for the year, and a Caper decided to have a nosey round the freshly vacated nest! Not seen one myself unfortunately 🙁
All my other favourites have already been mentioned above I think
Sea Eagle being mobbed by gulls on Mull, Sparrowhawk swooping at the Coal Tits at Glenmore, lots of close ups of buzzards.
I get a kick out of seeing skeins on geese approaching, I think the best was camping in Glen Truim and hearing them well before I saw them as they flew up the Glen.
My favourite sighting was probably the snipe outside Shenavall bothy, I’d been standing for age listening to him and then saw him zig-zagging up and down over the ground.
Three juvenile hen harriers above Rannoch Moor, they were literally shaking themselves like dogs after a viscious downpour which had maybe driven them to ground?