1) Monitors usually last long. As a rule of thumb longer warranty means, the manufacturer trusts its own product, and it will in fact last longer.
2) Build quality or picture quality? Response time/colour acuracy/ contrast what are your priorities exacty?
3) Do you mean overclocking? I do not really undertand that one.
Out of the two I would definitely go with the Benw PD2700Q !
Very similar models for a bit less are the BenQ GW2765HE and GW2765HT !
If you write more about your use case and give a max budget I am happy to recommend other models too!