Pier F is best overall, with the shower rooms, foot massage (if that's your thing) and the sit-down restaurant which I've always found has a wider and better range of food than the Wing F, but as others have said the Pier F is distant if you're leaving on BA (last time I was there in November, I arrived on CX to a gate near the Pier F, so went there and had a pleasant walk to the BA gate at 16).
Wing F's only special feature is the cabanas, which are wonderful, but odds of getting them aren't good unless you are going to be in the lounge for >hour. Having said that I got one in < half an hour while eating in the restaurant there. Restaurant is ok, but a poor second to the Pier IMHO.
Haven't bothered with the CX C lounges for a while, but the QF one is decent in terms of showers, the bar and there are trolleys with hot snacks that circulate early evenings (corresponding to when the QF flights leave), but that ends a couple of hours before the BA departures. The Bridge is fun for having pizzas, a barista bar and a "proper" bar too (but the Pier and Wing F both have bars), and is on the way between the Pier and the Wing/QF lounges. Haven't tried the Deck