20Mhz, 100Mhz better for digital
Tektronics are good
I would look for Leader, Goldstar, Kikusui (if that's how they spell it), Hameg etc.

.5mV sensitivity common

Tektronix 2246 or 465M (Ebay)

2215 (same as 2235, but 60MHz)
465 --slightly older than 22xx series, but good stuff w/ similar specs
466 same as 465, with built-in DMM
475 same as 465 but 200MHz 

Get Dual Trace

Good Tektronix
465 (25,00+ serials)
465B
475 475A
2235/A
Avoid: 2205,2225
2230,2232 must work (non repairable)
2213/2215 but watch for glossy CRT's
Avoid: 464,466 (orphan models)

HP Scopes
1740A and 1741A