I'm with EasyPeezy and use 1.8 on the Janome 6600 as well ... same reasons!
The finer stitching creates a sharper seam, without the shifting you get with the longer stitches.
While the default as mentioned above is 2.2 ..... I changed it to the 1.8.
Also, I changed the needle position of 3.5 default .... to 4.5 as that's where my needle needs to sit for 1/4" seams.