It's great that you're looking to change from Mettler's cotton. Not only is it getting lintier, when I did a review of the cost of thread back in April, I found out that it's one of the most expensive threads you can buy (of the main ones I reviewed), second only to Superior's King Tut. Incidentally, Aurifil came in the 3rd least expensive.
I haven't had time to do the shoot out for the threads themselves, but here's the price comparison:
http://www.archaicarcane.com/common-...ost-of-thread/