For a startup at the early ideation stage, which of these product management software is the best?

That’s sort of like going into a pharmacy and asking: what medicine is the best?  It all depends on the specific problem.

When it comes to IT, only once you know the specific needs and requirements, can you determine which product is the best.

I’m curious why others answered the way they did.

From my personal startup experience (multiple organizations each ranging from 12-100 people), uniformly the aim was to spend money as wisely as we could. Engineers were using JIRA, and the number of engineers far outstripped the number of product people, so the product function aligned with engineering to use JIRA.

The positive outcome was everything in one place so you have a unified workflow, expedited conversations, no integrations to fuss over, and for a time it was easier to align on decisions.

The downside - as the teams grew or as product requirements evolved, the amount of data in JIRA became very challenging to sift through, and the access/transparency generated questions about priorities which affected collaboration and efficiency... many cycles wasted trying to clear up confusion.