As others have mentioned, there are a lot of options out there, so more information will likely get you a response more relevant to your situation:
- Price constraints?
- Preference for new vs. used vs. DIY?
- Space constraints? (Can footers extend out to the sides, or would this prevent near-wall placements, etc.?)
- Floor construction? (Concrete slab vs. suspended wood floor vs. other)
- Floor finish? (high pile carpet vs. low pile carpet vs. other carpet/rug vs. wood vs. tile vs. other hard surface?)
- Does the sub have threaded inserts or are you looking for a platform style product?
- Expected weight and dimensions of subwoofer? (Footprint dimensions are especially relevant to platform style solutions.)
- Country from which you'll be ordering? (Can affect availability significantly sometimes.)
- Do you need a solution that can adjust for weight distribution? (Some subs can be pretty front heavy if it's a single driver and the amp is external and thus not counterbalancing the driver.)
I have low-pile carpet over OSB sub-floor on top of engineered I-joist suspended wood structure. I splurged and ordered Townshend Audio Podiums from the UK to put under my mains stack (large 2 way monitors on top of subwoofers having a matching footprint) and was amazed at the difference over the Herbie's gliders that I'd had previously. (I still use and like Herbie's products elsewhere, however, including between the mains and the subs.) The Podiums have flat feet, however, so I put a large tile under the Podium footers, on top of the carpet, to remove the variability in their footing. (I would be tempted to do something similar for any non-spiked solution if placing the subs on carpet / rug.) These platforms can accommodate an uneven weight distribution, which is helpful in my case, though more due to the front-heavy nature of my mains than the subs under them, as the subs are a dual-opposed design.
I couldn't allocate the funds to put Townshend products under my 4 other subs, however, and went with Isoacoustics Gaia footers and their separately available spike platforms to pierce through the carpet to the OSB sub-floor - another definite improvement. (I got mine on sale at an audio show.) Note that both families of products, and quite a few others, offer multiple versions tuned to a specific weight range.
Good luck with your project!