In Russia, I've used a double hander 90% of the time. Mostly Burkheimer 1398, also Scott 1509.
In New Brunswick, same double handers 30% of the time. Single handed more appropriate for the water I fish.
On the Gaspé, single hander probably 70% of time, double handers the rest when water is appropriate.
North Umpqua, double hander probably 80% of the time. Same rods as above, but also use Burkheimer 1338.
I'm really partial to the SA XLT. 7/8 for the 1338, 8/9 for the 1398, 9/10 for the 1509. I also use Windcutters when absolutely necessary and will shortly begin experimenting with a shooting head (underhand) for a few select spots in Russia (plus I like learning new things.)
Absolute favorite single hander is the old 2pc Sage RPL 10' for 8. Line is Wulff triangle taper, both floating and sink tip. I can't imagine a better, smoother, more satisfying combination. Can fish all day without tiring. Combo just seems automatic. Sage discontinued the rod many years ago. The 3 piece rods don't compare. I was so paranoid something might happen to mine that I bought a second one used.