So would you recommend to use a knot that is synched down or a knot with a loop? Sometimes I think when I synch it down the mainline doesn't come out of the knot perfectly straight and causes my crankbait to steer to the left or right and impedes the actions but I could be all wet on that.  

I think it is better to use "knots" that are not actually a knot. All the slips are excellent knots for any bait. If I had to pick it would be San Diego Jam and a Uni. They both are easy to tie and are slips.

Palomar with a snap.

I've always tied direct using a Uni Knot.  I don't want the knot in the split section of the ring.  I don't want the split section of the ring to be located at the lure's eye loop.  This requires more time than I like to spend changing lures.  However, after reading a thread on another forum, I believe I will remove the split ring from a couple crankbaits and try a Norman's Speed Clip and maybe a Decoy Egg Snap...both with and without the lure's split ring.  These 2 items look like they would not interfere with the lure's action while making it much faster to change lures,

No swivel and I use either the Palomar or Improved Clinch knot..