Planter selection- sealer choices

For longevity with watering -with plant use, what would the perfect planter pot type to do an image like this be?
Plastic, sealed ceramic or terracotta?
I am thinking the plastic or sealed ceramic with a clear top coat sealer.
A slick sealed surface would be protected but perhaps more difficult for paint to adhere to compared to terracotta.

This image is begging for some sedum placement.

Additionally what is your favorite sheen sealer to use and why?
I had been favoring clear Satin 2X also have matte and gloss and Rustoleum never rust clear sealers. Recently purchased 2X semigloss have yet to try it. Sometimes too many choices confuse me. I have not had opportunity to try a side by side comparison.