The popularity of chips is generally inverse to denomination. IMO, the order is probably: $1 most popular; then fractionals; then $2.50 and $5. The $25's are getting more popular, but only in recent years except for a smaller group of collectors; very few collect $100's and almost no $500 collectors. Many collectors will collect $x value "and down", meaning they collect $5's and also anything less ($2.50, $1, fractionals), so this makes the lower denominations even more in demand, cumulatively speaking.

When you see $25's, $100's+ priced below face value it almost always means that these became available to the collector market after the casino closed and they were no longer cashable. Therefore, they are only worth what someone is willing to pay for that "round piece of clay". This also means that a substantial quantity (box; boxes; whole rack) may have been saved from destruction, and if so, a moderate-to-low demand for these $25's+ vs. a more-than-adequate supply translates into a less than face value price.

In contrast, even if boxes of the lower value ($5 and less) chips come out, there's generally enough demand to absorb them into private collections at face or above, over time. These chips may not ever escalate much in value (beyond face), but you won't see values "crash" because they don't as far to fall.

For high value chips that didn't ever get out except when originally purchased at face value, a price above face (sometimes a multiple of face) is still the norm.

Bottom line, you need to know what your downside risk is if you collect high value chips off the tables at face value, because the day may come when the casino closes and a box or more becomes available at less than face. On the other hand, you may eventually have a chip that very few other collecors have. It all depends.

BTW, Atlantic City is the exception to this below-face rule, because of their destruction and redemption policies (excluding notched or NCV type chips). Some older, and even newer obsolete Nevada chips survived destruction, particularly if related to a bankruptcy closure, it seems. But each case is different. California clubs and Indian casinos have no specific destruction policies. I'm not familiar with other jurisdictions.