Hey everyone, can anyone tell me what is the best 3D camera tracking software for Houdini?

there are some product on the market. it depends on the requirement, budget and if you have already tools that has build in tracker (cinema 4D, Nuke).
i think today you can use nearly any camera tracking software in houdini

SynthEyes is surly a top product.
https://www.ssontech.com/ [www.ssontech.com]

PFTrack
https://www.thepixelfarm.co.uk/pftrack/ [www.thepixelfarm.co.uk]

there is also Mocha:
https://borisfx.com/products/mocha-pro/ [borisfx.com]

good luck.

If you're cheap (like I am), then use Blender and export as an Alembic. That's what I do and it works very well.