Anything pre-1980 or so is going to be pretty solid, nowmatter what color.
We had an old 1950 ish case, 4 cyl beast. Rated somewhere around 24 drawbar hp (felt like a lot more than that, used it to drag full size trees out of the woods more than once). That thing always ran great, seized up a couple times from rust (sat outside, winters can be harsh), unseized it with a breaker bar and some marvel mystery oil and it would run like new again. Finally got rid of it last year when we found coolant in the oil.
We currently have a 23hp diesel kubota, 1970 something. runs amazing, perfect little farm tractor. Worked wonders when we pulled the engine out of my yota.
We also have a 1980s JD 316, this is the most amazing lawn tractor i have ever used. Power steering, full hydraulics, 18hp onan (burns a lil oil), has enough power to easily mow 6"+ grass at half throttle. had an external oil cooler for the hydrostatic trans, you can get bucket kits, tiller, snow blowers for it...great tractor.