In terms of most popular chips a decade ago or longer, I’d probably start with the Paulson Chips mold sets in 2005, and specifically the Pharoah’s Club set. Much of the core membership of this forum (who largely migrated here in late 2014) was previously involved in a chip discussion site that was formed around the time of that set.
As Inca911 and others have mentioned, Vineyards were also quite popular then, and Ritz, Condado, Crystal Park, and Olivia’s were nicer, rarer sets of the day. The leaded, Paulson THC fantasy lines were still cheaper and more abundant too, such as Le Cove, Scandia, ‘98 CDI, etc.
It’s been 10 or 12 years since China Clay Chips became a thing, so those were pretty popular a decade ago I guess.
Some folks more familiar with Jim’s ChipRoom sales can probably list off some of the popular early retired casino sets that were made available ten years ago. Empress and PCA might have been that long ago.
The influx of retired casino chips to the home market, coupled with the exit of 2-3 of the 4 major compression clay chip manufacturers, changed the chipping game in a big way over the time period you are asking about. There are also some neat hybrid ceramic and injection-molded alternatives now that did not exist then. Chipco ceramics were available as customs instead.