Linux or Windows? I am thinking about buying a new pc and wanted the most stable platform!

It really depends on what you prioritize—stability or familiarity.

I'd say Linux, I use Mint 21.3, Houdini is much faster with it than Windows, I find it to be more stable too, and you can run both Windows and Linux on the same PC, in case you absolutely need some Windows only apps!

Linux Mint [linuxmint.com]

This may or may not be relevant to the OP's personal situation, but:

We've been using Houdini on Linux for like 15(?) years now, and never had any issues with it other than specific failures like our nvidia driver having certain bugs, or the linux distros going to far ahead of the houdini linux builds. In case of the latter Houdini is probably the software best suited for it, since they often react timely to issues like glibc-incompatibilities with bleeding edge versions.

I find that especially with larger core counts and AMD cpus, the Linux edition performs better.

That said: a lot of videos you see by the developers obviously use some windows laptops, so the difference for a single seat may not warrant a full OS switch, if there's no prior linux experience.

I would nevertheless give it a try.

In my previous tests I was getting 10-15% faster renders on Linux compared to Windows, having the latest Nvidia drivers is essential though, assuming that you have an Nvidia GPU.

Usually you need special procedure to get the latest Nvidia drivers, like adding the proper drivers' repository, here is how you install the latest drivers on Linux Mint or Ubuntu...

Add this repository to your Linux Mint system by running the following command in a terminal:

sudo add-apt-repository ppa:graphics-drivers/ppa -y

With the PPA imported, run an APT update:

sudo apt update

Next, enter the following command in the terminal to display recommendations for your graphics card:

ubuntu-drivers devices

If you are satisfied with the recommended version, use this command to install it:

sudo ubuntu-drivers autoinstall

Alternatively, you can install a specific driver version by choosing from the commands below:

sudo apt install nvidia-driver-555

Once the installation is complete, reboot your system for the changes to take effect:

reboot

Hope this helps