No idea about Optimum, but just thought I'd mention that we gave up out landline back in August and haven't missed it. We're both on the same cell provider, so calls between us are free.
we didn't have a landline until we had kids. If you don't have kids, I'd agree with everyone else and say that you don't need it. We just felt more comfortable having a cell and landline with kids, since my aunt watches them in our home. She does have a cell phone, but we also wanted a landline. Sorry, no advice about specific companies.