What would the most valuable quantum solver look like, from an algorithmic perspective?

A Reddit discussion explores the most practical applications for large-scale, fault-tolerant quantum computers capable of deep non-Clifford circuits, focusing on real-world algorithmic value. Top contenders include QUBO/Ising optimizers (QAOA-style) that outperform classical heuristics on NP-hard problems like routing and scheduling, offering tangible industrial benefits. Quantum chemistry engines (QPE, qubitization, VQE) emerge as another frontrunner, promising scalable ground-state energy calculations and reaction modeling for drug discovery and materials science. Shor-class cryptanalysis remains theoretically powerful but faces limited near-term economic impact due to post-quantum encryption adoption and regulatory constraints. "Killer app" criteria hinge on provable speedups, problem scalability, economic viability, and verifiable outputs—prioritizing measurable advantages over theoretical potential.