I used Mettler thread for years in my Bernina sewing machine, but have finally decided it creates too much lint.
Have heard that Aurifil creates much less lint, so that is what I am going to try now. It's a thinner thread too so that more yardage fits on a bobbin. I'm ordering from the website below that someone else here recommended, as she is having a sale on Aurifil (50 wt is the one I'm planning to use for piecing) for $6 a spool thru December 31st. (Yikes, have to get my order in!)
http://www.sewezdesigns.com/index.html
Have also seen Masterpiece from Superior Threads highly recommended for piecing. It seems to me it is very similar to Aurifil, and I think I figured out that Aurifil is cheaper.
King Tut is often recommended for machine quilting. It is a little thicker than Aurifil and 3-ply instead of 2-ply. I am going to try the Aurifil variegated for machine quilting, but I'm tempted by the King Tut as it would be a stronger thread. It's just that it is about twice as expensive as the Aurifil on sale.