In HO, add Bowser, Funaro and Carmalengo, Chooch, Red Caboose, Mantua(especially their "Classics" line), BranchLine, Rivarossi, LifeLike Proto 1000 and 2000....... All better than ConCor(I wouldn't walk across the street if they were giving these away) or plain Bachmann. Bachmann's Spectrum line is nice, but Bachmann's quality ends there.
And I guess that we can add Athearn Blue Box and call them "mainstream". There are still enough of them to last a long time, even if Athearn decided to screw the pooch and discontinue them. Dollar for dollar, they are STILL the best buy. And I'd bet a dollar to a donut that there are more Athearn BB cars riding the rails than any other manufacturer offering.