Best Security Plugin & firewall

I was experiencing problems with some “crawlers”, my page contains more than 5000 entries, with a lot of content (text, images, videos) … the bots are indexing it again and they were saturating me to the point of having knocked the web down several times … now I can control the request rate and free the server from so much load … after having tried various applications, the only one that gave me good results was “Web Application Firewall” … now I can control access attempts, block malicious users and control the way bots, spyders and crawlers access my page without saturating the server resources