Why don't many companies use custom seals?
I think it is because it may be too expensive to create a custom seal for a small run, ie, theory 11 never use them because they always have small runs.
What is your favorite custom seal?
Favorite would be, either Arcane, Ghost or Vortex, all very nice designs, but as Phantom said, I prefer decks with NO SEAL AT ALL, because you have easy access, doesn't look crappy when you open the seal and it rips and if you fully take it off, it leaves a sticky residue.
Would you like to see more custom seals being used on decks?
I would love to see more custom seals, but also more decks with no seals like the crowns or steampunks.