k41te45

Too low surface tension may be good for the substrate wetting but may lead also to a wavy surface.
Too high surface tension can cause adhesion and surface wetting issues.

If you are exploring the factors that govern leveling in any formulation, it might be worth to begin with an in-depth understanding of leveling basics (surface tension, contact angle, test method, etc.) at first.
Which leveling agent is suitable for your formulation?
There are several base chemistries to choose from when selecting a leveling agent & lower the surface tension to the point just that you need for a desired application.

The most common types of leveling agents are listed below.

Silicone-based agents (Polydimethylsiloxane modified - PDMS)
Acrylate-based agents (Polyacrylate)
Fluorocarbon-based agents (Modified Fluorocarbons)
Hydrocarbon-based leveling agents: less efficient than previous families

Understand each chemistry in detail and see which one fits best for your formulation & end-application needs.