Buy what you like or can afford. I like the Hood Leatherette fitted covers. Or buy an inexpensive vinyl cover.(looks like shower curtain liner).
Either one will protect the table.
Covers run about $7.99 -$100. Look at Muellers, Seyberts or Ozone, They have a great selection.
I got one off Ebay for for my 9' GC. Fitted with about 8"-10" of skirt made of leather-looking vinyl. It was cheap and works great although I can see some daylight through some cat claw holes. Cloth seems to be fine though. For the price (I believe around $90 delivered IIRC), I'm very happy.
Best protective covers are made from marine grade naugahyde and typically are fitted for the table. If you play a lot and just want to keep the dust off the table then one of the cheapo thin vinyl covers is fine.