i prefer Whittles they sell popular lines from Marcus, Hoffman, Benartex, etc - so if you are happy with that quality you will be happy with Whittles.
Connecting Threads sells their own line of fabric.
i feel with Connecting Threads you get what you pay for, cheap prices = cheap fabrics.
i feel with Whittles you get more then what you pay for,
cheap prices = LQS quality fabrics.