I also like Aurifil but simply cannot afford it for day-to-day piecing.
i have relied upon connecting threads 50wt for just about everything.
I recently tried YLI Soft Touch, just for giggles.
I like it and all my machines like it, too.
(My Brother brand machines work better with 60wt. top thread)
the YLIST is about $20 for 6,000 yards. about $5 for 1,000 yards. (
https://www.uncommonthread.com/YLI-S...read-s/159.htm)
compared to $45.95 for 6,452 yd of 50 wt Aurifil, or an average of at least $10 for 1,500 yd, YLIST comes out the clear winner for me.