Finding the right sculptor and commissioning a work that rewards your hopes should never be a lottery. You need to rely on just one factor: reputation. The artist should be well known for producing consistently excellent work.
By excellent, I mean their sculptures are in high public and private demand, appear in the permanent collections of respected galleries, museums and other public displays, and command significant prices.
This is relatively easy for the collector or person looking to commission the sculpture. The same cannot be said for the sculptor who must endure years of hard and often thankless labour to build their reputation.