There are plenty of good marked decks out there. The MINT decks by 52Kards is my favorite, but I also like the Kings by E. I've also heard great things about David Blaine's White Lions.
You could also get a reader. The Ultimate Marked deck, the Red Keepers, and the Vintage 1800's marked deck by E are all great readers, and there are plenty more out there.
There are a few decks out there that were made to function like a non-marked deck, but have a built in design that can be Marked. I can only think of David Blaine's Split Spades and Daniel Madison's Hellions (hopefully out soon) off the top of my head, but I'm sure there are many more.
However, I do think the greatest marked deck is one you make your self. You can come up with your own marking system, which is what I reccomend, or use one already made. There is the classic Bicycle Marking System, which you can find almost anywhere on the internet. However, you can buy videos/texts on marking systems other Magicians have made. The Blood Marking System by DM is a great example.