Is it possible to convert from TN1 to L1B after I already moved to US?

[myicc]

I was working in Canada for a US based company and got transferred to US. Funnily the company lawyer did not present me the option to go L1B and just did my TN. Now I am in US under TN and just realized I could have done L1.
Can I still convert to L1? Is it better to just do H1B or L1B now?