5.3 is certainly “better” than its flash variant, in my experience. I’ve moved on from both but eagerly await the next generation of each.

Better, in this context, is more capable with open ended work, planning, longer horizon “reasoning”. Flash is an absolute chad with a well defined task and accompanying guidance/guardrails/conventions provided. But not even close when it needs to deviate, runs into a “blocker” and has to reason its way out.