That is a quite subjective question, so here is my the quite subjective answer.
I would look to:
- Price including agent fees and deposit
- Neighbourhood: infrastructure, criminal situation, recreation areas or points of interest
- Time travel to workplace
- Owner's common sense and openness: I would discuss possible scenarios like broken washing machine, required balcony chairs, problems with hitting
- Facilities in building and furniture in the apartment: is it fresh or recently re-decorated, how good isolated, double glassed, check mould in corners and bathroom
- Read contract: what are termination conditions, what are rent increase conditions, what are procedure for deposit return
However, with the current situation on the rent market in Amsterdam and neighbourhood, I should much my criteria and make decisions super fast. I should also trust a lot my intuition since in such short amount of time brain can not make proper conclusions.
If you have free money I would advise to go with an agent who will help you with finding, he will save your time, he will check your required conditions and can speak landlord or his agent language.