Boy, I do have some favorite quilts but don't know so much about favorite pattern or block. I've done a lot of quilts using Snowball blocks as alternate blocks. Works well to tie in busy blocks, or to use for a large scale focus print. I've done a number of Log Cabins and variations.
I think my favorites are always what's next or what's in the planning stage. Then by the time it's done, I'm usually happy to give it away and never look at it again. If the give-away isn't immediate and the quilt stays around for a bit, i start appreciating it a bit more. Every now and then I get a project that I just enjoy the whole process, unless those were meant to go to someone some of those donations become keepers.
edit/for the OP -- lately I'm using this Simplish concept a lot when I'm making donation quilts. While the one shown here is rather calm, what I like is it is a way to take a wide collection of related fabrics that maybe don't look so good next to each other and make it usable.
https://www.youtube.com/watch?v=3K76_K7ZcvI
This cuts down from 10" squares nicely, and that is usually what I use, around Y2K I did a lot of swapping and I have a lot of squares! A couple of years ago I gave away a collection of Angel fabrics because I just couldn't think of any way to put them together. Of course, almost immediately after that I came across this pattern due to one of our fellow board members and I realized that all I ever had to do was use black for the sashing and those angels would transform into a stained glass window...
Whew! Got the edit in time. Here's two I've done, Here Kitty Kitty was from those swapping squares. It was an accident that I ran out of the fur fabric for the sashing and had to add in the black. The other I call "Horse Blanket" and I added the rows of just squares top and bottom.