Tektronix, B&K Precision, LeCroy.
Kit scopes from Heathkit, Knight and Eico
If you're going to work with tube equipment the older scopes tolerate more abuse.
The folks on the Yahoo Tektronix and HP/Agilent/Keysight newsgroups are helpful. If you post what you're looking for offers will come out of the woodwork.
Dittto the ham radio flea markets.
My everyday scopes are Tek TDS3012B and 2465B. I use a 5223 for low noise. I took in a new version of the TDS and since Tektronix was purchased by Danaher, you just might as well buy what you want from China. The TDS 3012B uses floppies!