Here's my two cents:
First, decide if you're in the rent for a year at a time market or want a place to stay in for multiple years. A realtor is probably a necessary evil if you want a multi-year unfurnished lease.
For everything else and particularly for furnished rentals, Airbnb is a better option. There's lots of availability on Airbnb now, the prices are lower than with realtors and it's a much better experience. If you do an Airbnb and want to stay you can do a deal with the owner to lower the price 15% further. Airbnb rentals are also way more motivated to keep you happy due to the reputation system.
Realtors overall are horrible in BA - even worse than elsewhere. In the sub-market that is furnished rentals of less than two years they charge high fees (1-2 months rent commission for each contract), ask for guarantees (more paperwork/cost), are dishonest and will drown you in contracts. Lots of stories around about realtors stealing deposits after exit. For a furnished rental in my experience the cost with a realtor is usually 25% more than Airbnb with way more hassle.