Love planning, cutting, piecing and binding a quilt! However, the actual quilting process - from determining the motif to quilting FMQ or with rulers - is the most challenging step for me. Sometimes, it's my least favorite because it's not as easy to do but it's always the most rewarding when finished. The same goes for paper piecing and curved blocks - not my favorite while doing it but always rewarding in the end.
Oddly enough - I also enjoy the process of organizing my sewing area and tidying up after sewing. I find it enjoyable to step into a clean and organized sewing room so that I can get busy creating.