I originally wrote this a while back on SOTW and it has proven useful and accurate for many people.  I’ve decided to post it here for easy searching and preservation.  Enjoy:

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It really depends on one’s taste. It is not so much that particular serial number ranges are better than others but that they have different bore designs and offer different tone color or response than others due to that. Below is for tenors, I don’t know altos well enough.

Some of the tendencies are very reliable, some are not.
Mid 50k to mid 60k still have a lot of the color of late SBA tenors. They are in my experience, without exception, very warm players. They tend towards bright and fast response and have a type of elastic expansive bounce to the response. They also tend towards spread, but that definitely has variance.
Mid 60k-late 70k is a progression from increasing focus and power to possibly more spread at the later end. Still very warm, but more aggressive, less elasticity in the response than the 60’s. 70k tenors are all over the map, lots of experimentation going on in this period.

Early 80k is in my experienced a powerfully loud and fairly spread horn with an edge when pushed and a lush low end, with a bit of resistance to push against.
mid to late 80k tend to be significantly more focused, brighter, with very little resistance, if any.
80k series also progresses from having perhaps 2/3rds of the warmth of the 60-70k’s to having maybe 1/2 of it by the end, and then less later. The warmth is traded for edge and power in this case.

90k are heading in the same direction, but share the same experimentation situation as the 70k tenors; they sound similar to 80k tenors but the air pressure is different, some are successful, some are not. 100k – mid 120k is a solid run of focused punchy bright and compact balance. 130-mid 140k has it’s own character, maybe more spread than 120’s, big sound, and a power and balance that kind of culminates around 140k which is reputed to be a revisit of the bore size of the 80ks.

150k-mid 160k is the last bits of the vintage feel and by then only a tiny bit anyhow, they are solid top of the line instruments, and are very functional most of them, quite reliable in my experience, but more generic as well. After mid 160k they can be extremely consistent and extremely generic, and good instruments as well, but simply not the vintage vibe.

In terms of the vintage vibe, the most consistent periods in my experience are 50k, mid 60k, and 80k. That does not mean they are the ‘best’, just the most reliable in terms of their response. 70k you can get an absolutely excellent horn, but a few numbers later something totally different, same goes for early 60k, 90k, and all the SBA’s (LOL).

There are great and unique horns in every period, and one man’s junk is another man’s treasure; you might love the horn I think is crap, but these are just my impressions from playing a lot of them. The idea that there are ‘dogs’ in every period is, in my experience, not true. Some period have no bad horns at all.