I would say most collectors of Timex would use the term rare to describe watches that fit #2a such as the Dorado. It is different as it is the only solid gold Timex but not rare in the sense of #3 in that they can readily be found. A better term than rare might be unique but that doesn't have the ad pizazz. Same goes for the Hogans.
Term #3 (aside from condition) might describe one such as the Electro-Alarm which I doubt you will find many more than the 2 I am aware of in years of watching. Or others might be the one with a light on the crystal and the battery and switch in the band or the back wind electric with a display back. JMHO