The old ones are the "good" ones, is the common belief. They all attract unreasonable prices I think. Take the GB name off and you can get some really nice Adam cues, both old and new for a lot less.
I have noticed sellers from Japan lately selling what I think are ADAM models that were not typically available in the US.
So, if how it plays is the priority, newer models will likely play more up to modern standards, especially with an aftermarket shaft.
With all that said, these GB cues do hold value. There is a whole line of famous maker and famous champion cues from Adam as well that tend to hold value as they were made in limited numbers. The funny thing is, the GB cues tend to be the most numerous, most available, but have the strongest value. Chalk it up to the lasting effects of TCOM I think. Even JOSS features TCOM right on their front web page.
Adam was and is a prolific cue maker, and most will say their cues are generally very good. Whether or not it plays "good" relative to newer cues or other cue brands will be best determined by the owner I think.
I have always thought to have an Adam GB cue in my collection, but never bought one. I just don't like the prices. I have more rare Adam cues that I got cheaper.
Yup...TCOM is still a marketable thing.