For high torque applications you want to maximize motor radius over axial length. See my previous post.
How to select BLDC motor for high torque applications
In addition, you want to use the highest energy product magnets possible (Referred to as BHmax). The energy product is generally proportional to motor torque. The competing issue is that the higher energy product magnets you select the less thermally stable the magnets are. So you have to balance temperature vs torque. I think most motor designers usually use something close to a N45SH grade magnet material.
In terms of winding patterns there are formulas you can use. I would recommend Duane C. Hanselman book: "Brushless Permanent Magnet Motor Design 2nd Edition". This book provides an appendix with many different winding combinations and the associated harmonics that you would definitely find useful.