From my experience, picking the right partner is very important. For example, in two companies I seeded, the same top tier VC firm invested in later rounds. In one case the partner has been super helpful, and in the other case pretty much absent. The partner’s influence within the firm also matters. A influential partner can, for example, “pound the table” to do a follow on financing when you need it. What stage the partner is in his career also matters. Junior partners will typically work harder, but might also have “sharper elbows” when, for example, you are selling the company since he needs to prove himself by making the firm money.