Part of me realizes that there’s no such thing as a “failed” scientific experiment and that diversity of approaches is good. The other part of me thinks that a public and competitive spectacle would also be good.
Technology for magnetic enclosure was advanced significantly by both. In this regard, they profit from each other.
Tokamak reactors require a pulsed operation mode. There is no way to sustain fusion for longer time.
The Stellarators design allows continuous operation, putting less stress on the structure. The calculation of the winded enclosure structure is quite complex and it has only become possible to design and implement with sufficient precision recently.
If I'd have to "bet" on a design, it would be Stellarator. If you understand German, listen to this podcast. You won't regret it: https://alternativlos.org/36/
The design for the 7-X wasn't feasible until supercomputers got powerful enough. We know how to run those simulations; fusion should get more practical as computers get faster.
Key takeaway:
Thanks to progress in superconductive magnets, a new reactor type developed by the MIT called SPARC might likely become the first Fusion Reactor to achieve net energy output before 2030, producing 200MW in 1/65th the volume of the ITER design, at a fraction of the costs.
All based on very solid physics with only littly uncertainty remaining. Wow.
[0] https://en.wikipedia.org/wiki/SPARC_(tokamak)
Also: all other designs don't even come close to fulfilling this promise.