They are very different experiences.
Tabaq is known for the view in its upstairs area but it is very dark therre and not a good place to eat. Have a drink, enjoy the view, and then eat downstairs. Mostly small plates . It is very casual.
Bistro Bis is upscale French bistro. More formal in every way than Tabaq. Better food, better service.
Your choice depnds on what you want.
I've never been to Bostro Bis, but I ate at Tabaq a couple of months ago. We had the tapas there. and they were pretty good. It's kind of a "fu fu" scene. There's an open roofdeck dining area, which is a lot of fun during the warmer months. I think this would be an ok place for NYE, but I guess it all depends what you're looking for.