Mostly dock, unless I am playing in bed or something, which I rarely do The handheld is pretty heavy and hurts my wrists and shoulder, so I try to avoid playing on it.
I got 2 monitors on my desk. When I want to play on my Switch, I move the HDMI-In on my capture card from the PC to the Switch. Takes a few seconds. This leaves me with 1 Screen to the Switch, and 1 screen still functional for the PC. So I can use both simultaneously at my desk.
I love to play on the television and I'll go through long spells of doing so when I am very free and have lots of time to kill. However, since that is rarely the case anymore, I usually resort to handheld. I also have a second Switch which is a Lite (which I only play/use in Russian, for practice) so I only play handheld on that one.