When I sold my parents' house on La Marina last year, I used:
https://newstartestates.com/At that time, they were charging 3% or Eu 3,000 minimum.
When comparing services, ask which property portals they advertise on.
Personally, I would steer clear of any agent that doesn't have a clear pricing structure. The types that want to add their commission on top of your agreed selling price don't offer enough transparency and this arrangement can work against the vendor. Friends of ours recently bought a house from a Dutch agent: a few weeks after completion, a chap appeared at their gate, saying he was the brother of the previous owner and would they tell him how much they'd paid for the property. It transpired that the agent had told the owner they needed to reduce the selling price, which they did, but in fact he'd taken that reduction out of the vendor's proceeds whilst protecting his own commission. These types of agent bank on the vendor and purchaser not speaking directly to each other, but my friends discovered that, of the Eu100k they paid for their property, Eu30k went to the agent! When the agent suggested the owners drop their selling price, he wasn't taking a hit on his own commision. No odds to my friends, but needless to say, the vendor's brother was not happy to hear this.