Which is more important: to hire a candidate with high competency but less experience or an experienced candidate who is not very competent?

competent condidate of course

If the organizational culture encourages innovation, relaxed hiring policies, works in a fast pace industry, I would hire a high competent person.
If organization is strict in policies with a vertical organizational structure I would hire an experience candidate.

Competent candidate but flexible and fast learner

Less experencd candidates are usually hired at entry level and they could polish themselves and progress the ladder. Similarly, less competent individuals remains onlower side. If every one is a STAR PERFOMER then who will compile the report? who will do the filing work? who will welcome the guests? every one has its own importance and role to perfomr in organization.

A high competent person can overcome the deficiencies of being less experienced but a low competent person cannot overcome the deficiencies of being less competent.