I love Loch Rannoch. This is the only one I'd actually be tempted to keep if I won (apart from some of the London ones, which would be handy and easy to run as holiday lets when not there). It's close enough for me to go there regularly and I would swim in the loch.
I don't love the layout though, with two of the bedrooms pretty much in a different building from the other two. I probably wouldn't want to put two small DCs that far away from us, so they'd have to share, which is a bit of a waste if you've got a massive house.