My take on this is the first Thompson tool I used was so good that I never felt tempted to try D-Way or Carter & Son. Other very high quality marques include Stuart Batty tools (which I got to see close-up when I hosted him the time he came to give a workshop at my turning club), and HannesTools (he gets his tool steel from Doug Thompson).
I suspect that if I'd tried one of the others first, that would have been my choice going forward.