Free synth plugins

I've been amazed by the quality of the free orchestral instruments by Spitfire. I wanted to find similar free plugins for synthesizers.

I asked ChatGPT and got a short list. The only one I was really able to use is Surge. Surge is free (open source) and comes with a bunch of presets which sound really nice. No account required. This will be the only synth I need for now.

Just for the record, here's the list of plugins I've tried from the most useful to the least useful, according to my very limited experience in synthesis:

1. Vital. Requires an account. The free version comes with 75 presets, which honestly sound really bad. Only 1 or 2 of them might be usable. The rest simply hurt my ears. Whatsmore I am too much of a beginner to create my own sounds. So for now I cannot use it.
2. Prism by Native Instruments: I don't know if it is free, but I got it as a bundle from my Komplete Kontrol M32 keyboard. The presets sound bad too. Also it has been incredibly difficult to use. In Kontakt, you supposedly can set up several synths, then set up your DAW to link one MIDI track to one synth. I was unable to do it.
3. OB-Xd: Sure you can download and install it for free. However if you open the VST3 build, it will show you the synth interface but it will be muted. And it will tell you that the VST3 version is locked. Only the VST2 version is free, but I was unable to find it in my DAW. I may have messed up the install. Still, I simply installed the default build.