I have had most of the great small monitors over the last 45 years: LS3/5a, Double LS3/5a, Braun Output-C, KEF 101, Celestion SL6, Spica, ProAc Tablette, Reference 3a mm de Capo, Silverline SR-16, and I must be forgetting one or two more. Any of these are "worth keeping" if you have them matched to appropriate amplification, but I also must point out that if you want or need a small monitor, there are a few modern alternatives that outclass every one of these in every way. Well, the current Ref 3a deCapo is in the realm.
1/ Audience ClairAudient 1+1 v3. Simply the best truly small monitor ever. No crossover, so it sounds impeccably coherent. Neutral but rich in tone; fast, transparent; expansive imaging and can output reasonable bass alone. Everything vintage will sound by comparison choked and small, however tonally neutral one might sound.
2/ If you don't have the $2800 or so for the above, the ClairAudient The One gets you the same basic attributes, with less scale and foundation, for a less than half that. And it fits in your palm.
3/ Zu Cube. A full Zu FRD with coaxial supertweeter, no crossover, stuffed in a 10.5" cube. Also intrinsically coherent. Very high resolution. These cost, depending on finish, between $1000 - $1400 pair but they demand no skimping on the amp. All the Zu essential virtues in a compact, sealed cube, with bass rolling off below 60Hz. 98db and robust, so power them with 2 watts or 200. They'll rock either way and won't break the bank.
Phil
