I think another critical factor is, if you don't sell off, will Google ultimately supplant your relevance and kill your market in the long run. If so, it might

I think another critical factor is, if you don't sell off, will Google ultimately supplant your relevance and kill your market in the long run. If so, it might be better to benefit from their investment than just be another forgotten casualty. How original is your idea? How easy is it to replicate? How common sense is your business model and if novel enough, is it protected and do you have the legal resources to defend it?