For me,the best tournament system is what Len had used for some years,at Water Polo European Championships.
12 teams,2 groups of 6,the first of each group qualifies for the semifinal,while second and third teams play an additional "quarterfinal" match"
You would argue that 12 teams for volleyball are few,but it could be counterweighed by strong qualification round,like:
-Every team except the host participates,no automatic qualifications to tournament based on perfomance at previous tournaments
-First and second round for "weak teams".Home and away matches.
-Third round 24 teams-,winners of second round and "strong" teams,6 groups of 4, 1 host team per group.single matches(3 per team).First two qualify for the tournament.