of course a good investor will first do its own research (whitepaper, roadmap and etc), besides that what is your biggest motivation?
Beside all you listed above my motivation is usually the team members, behind any successful business is a strong team. I look at the team behind a project before I even look at what they're selling. Because I believe a good business idea in the hands of the wrong team is useless but an average idea in the hands of a good team will turn to Gold