I've used Connecting Threads thread for the last couple of years and just recently switched to Bottom Line. I love how fine it is, and it just seems to blend and sink into the fabric so nicely. I originally switched because I was making miniatures and wanted a very fine thread that would decrease as much bulk as possible.

Superior Masterpiece thread. It's available in cones. I always keep black, light grey, dk grey and cream on hand. I use 90/14 needles as they go thru extra layers at seams well without missing a step even though the thread is 50 wt.

I use Aurifil thread and find it to be superior to other threads. My machine loves it and it isn't as "thick" as other threads. I use 50 wt for piecing.

I like Connecting Threads. I have some Metler and some Arifil and like them, but for my money Connecting Threads is the best buy IMHO. I like Schmitz needles, and never have any problem no matter what size I use. I also use Gutterman and I like it. Get it with coupons at JoAnn's. I am always on the lookout for sales, and usually use neutral colors. I like to wind many bobbins and then I'm off and running.
Sue

Handpiecing: Bottom Line 60wt or Mettler 60wt cotton and whatever needle is handy

Machine piecing: usually Aurifil 50wt with a #12 titanium needle or Bottom Line with a #10 titanium needle
Bottom Line in the bobbin regardless of the top thread.