The first thing you should pay attention to is the reputation and reliability of the company, convenience and profitability of the offered products, speed and availability of services.
Before the war, it was possible to check the validity of a financial institution's license on the NBU website. Unfortunately, in connection with the introduction of martial law in Ukraine, this service still functions with limitations.
It is important to read all the terms of the credit (mortgage) agreement and evaluate the financial company, taking into account all its pros and cons. In particular, these are payments for loan servicing services, additional commissions, fines for late payment, payments for additional services, etc.
Make sure that the creditor, if necessary, will come to your meeting and help solve problems (in today's conditions, this is very relevant).