H1b or TN?

Hello,

I am a canadian citizen and H1B holder. I will work with my current company until the end of this year and join a new company starting next year. I have two options for my visa status either remain with H1B or switch back to TN.

I am wondering if there is possibility I may be rejected for TN. The only reason I want to keep my H1B status is because I would like the company to sponsor my green card at some point. Which visa would be the best for me?

Thanks for your help