Recognizing that there's no truly objective way to evaluate subjective tastes, I will state that it is my opinion that GW miniatures are far from the best. In an effort to lean into branding and IP protection, GW miniatures are very pigeonholed in their designs. Whereas a company like Reaper puts out miniatures that could fulfill a variety of uses (D&D, Wargaming, general hobbying, etc), GW miniatures are strictly for AoS/40k. The kits haven't been customizable for almost a decade at this point. If you were to compare Free Company Militia to a modern GW release they'd appear to be from a completely different organization both in terms of aesthetics and overall function/design belief.
When I look at a miniature studio I can't help but look through the lens of what the underlying value prop is, and below I've just sort of rattled off a few along with my cursory thoughts.
For a company like Reaper, the value prop of their Bones line is very clear: Cheap, no assembly (or very little assembly) and durable. Which necessitates sacrificing fidelity/sculpt quality.
For a company like North Star, the value prop is: Cheap, highly customizable, with a wide variety of options that can be used in skirmish games as well as full-scale wargaming. They're also hard-plastic and can be kit-bashed with other companies also using hard-plasitc. The trade-off is again you're not getting high fidelity in the sculpts, and if you were to use them for individual characters, they probably won't compete with other studio's offerings.
For a company like Raging Heroes, the value prop is: Expensive, extremely detailed/intricate designs, and sculpts that can be used across a wide range of tabletop activities (D&D, wargaming characters, etc). The trade-off is you're not getting customization, and you're not getting plastic sculpts. You're dealing with resin, or metal, which for many is a deal-breaker.
When I look at GW, I see miniatures that are: Expensive, not particularly customizable, not particularly flexible in their usage, not particularly convenient to assemble. There's almost an absence of "value" in what GW brings to the table from a miniatures perspective. The reality is that the price of an AoS or 40k army at retail price from GW is going to fall somewhere north of $500 USD, and now you're competing with very different types of entertainment valuations or hobby valuations. For $500, you can get anything from an Xbox or Playstation to a high-resolution resin 3d printer.
On the subject of creativity and pushing the envelope, I believe that the truly talented up-and-coming sculptors are the ones in the 3dprinting space, which is undergoing a renaissance at the moment. The quality, detail, and look of the sculpts coming out of these independent studios is unbelievable. When I see studios like Archvillain Games putting out monthly releases that continue to push the boundaries of miniature design, I have an impossible time looking at GW's releases, and price points. The cost in electricity and resin to produce a high-resolution 32mm or 40mm model is pennies on the dollar versus Games Workshop, and even factoring in the upfront costs, I believe that buying a 3dprinter and the supporting materials (resin, mixing cups, etc) is substantially cheaper than buying an AoS or 40k army.
To close off, I've attached a picture of the GW Abhorrent Archregent next to the upcoming Archvillain Games vampire release to show a sort of apples-to-apples comparison of "the best" as I perceive it.