Normally, a company (either startup or not) cares most for its clients, because they are the ones that pay its topline and ultimately its workers' salaries. Other parties (users, providers, government, whatever) also have power and can also influence the company's behaviour, but clients normally have it easiest.

That does not always hold, as I said. Another example is you being a commodity client; if the company is, for example, more interested on big clients, your interests might not be the first concern for that company. But they will have you in mind, nonetheless, as the bad service you receive can signal something bad for bigger clients. Sometimes, even big clients are commodities, as they can't wield a lot of power, so the company can act not in its client's best interests (monopolies or tax burden when price is inelastic are scenarios that come quickly to mind).