The list of shows I plan on watching seems to have no end to it, and I download and keep most shows I'm interested in watching on reserve long before I get to them.
when I finish one show, what I watch after is decided by, what's done downloading and ready to go, what kind of anime the last one was (as sorted by 3 personal time zones) and what I feel like watching at that time.
and if I can't decide, I flip three quarter dollars, or one three times, going off two out of three.
to expand on the time zone thing, I sort my anime into three groups.
morning, kids anime.
evening, kind of general whatever time, while still somewhat lighthearted.
night, darker more serious themed possibly violent stuff.