I'm so glad there was a conversation about Aurifil thread. My husband just bought me a quilt kit that came with Aurifil and I wasn't sure what it was or if it was good! I am now more comfortable about getting it!
I usually use Gutermann thread, and sometimes Connecting Threads thread. Gutermann is a nice quality cotton thread with low lint that my Janome and I enjoy. The only thing I have a problem with Connecting Threads is it doesn't get along with applique and fused webbing -- it would skip stitches (which no other thread did). My all time favorite is Iris Ultra Cotton. It's resilient, but fine, and sews up beautifully. It is sold at Janome dealers though.