Indeed many factors play role I guess. May a survey will hep us get answers on 'What motivates a peer reviewer?' Thanks you colleagues for these answers.
Since you ask of the journal where you want to publish to find referees that can assess your manuscript, you better damn be willing and able to do that same duty as a referee - to repeatedly turn down requests from a journal editor to perform refereeing duties is darn right shameful! We do not call it "peer review" for nothing. We shall all reciprocate in kind - because that's how it works! It means that someone (or hopefully even 2-3) from another institute shall read and assess the manuscript, and suggest improvements, noting error corrections, and providing hints on papers to add to a literature survey, and so on. Without the peer review system we are doomed.