GPT-5.4-Cyber (OpenAI) vs StepFun Step 3.5 Flash

StepFun Step 3.5 Flash edges out GPT-5.4-Cyber (OpenAI) by 0.6 points (7.8 vs 7.2) -- a B-tier vs B-tier split that's narrow but real. Not a blowout; both belong on a shortlist. The score gap shows up most clearly in the categories that matter for StepFun Step 3.5 Flash's strengths, so if those categories are your priority, the lead translates.

On pricing, StepFun Step 3.5 Flash starts free while GPT-5.4-Cyber (OpenAI) requires a paid plan from day one (Not publicly disclosed+). If you're testing the waters or running an occasional workload, that gap matters more than the score differential. GPT-5.4-Cyber (OpenAI) starts at Not publicly disclosed; StepFun Step 3.5 Flash starts at $0. Compare what each entry tier actually unlocks before you compare list prices -- the limits matter more than the headline number.

By use case: pick GPT-5.4-Cyber (OpenAI) when enterprise soc teams, established security research orgs, and vetted individual defenders who can qualify for trusted access for cyber. Pick StepFun Step 3.5 Flash when teams building agent systems on chinese open-weight foundations who want something other than deepseek or qwen, especially if agentic tool-use is the primary workload. The two tools aren't fighting for the same person -- they're aiming at adjacent jobs that occasionally overlap. If you're squarely in StepFun Step 3.5 Flash's lane, the tier-list ranking and the use-case fit point the same direction; if you're in GPT-5.4-Cyber (OpenAI)'s lane, the score gap matters less than the fit.

Bottom line: StepFun Step 3.5 Flash is the safer default for most readers, but GPT-5.4-Cyber (OpenAI) is competitive enough that the tie-breaker is your specific workload, not the spec sheet.