If you can't get a TN Visa, your best bet would be a HB-1 or a greencard. - both if which are hard to get and require a US sponsor. For HB1 I've heard the for companies under 5 yesrd in age it can be difficult(and expensive with lawyer fees) to sponsor a candidate. However if you plan on living in the US beyond your visa both the TN and HB-1 won't help - you cannot seek P.R. wih these visas, so st this point a greencard is your best bet.
The fastest way to get a green card is to "be a notable person" which means you have to have at least two articles written about you and/or have publications in field that you are studying. At this point I would really talk to an experienced immigration lawyer (preferably wih experience with startups) to advise you on the best plan of action.