W2 or 1099 vs solo 401k and QBI

I’m an independent contractor.   I just changed the supplier that I go through, ( I work for a larger corporation but have to go through a supplier) and the supplier has a 401(k), but I don’t want to use it - I want to just do my own solo 401(k). And I want to continue to QBI 20% income reduction.

 

I can go through this supplier either as a 1099 or W-2 Contractor.   Are there tax consequences I need to consider related to solo 401k and QBI decision between the two?