For watching on the TV (via Roku) I use mainly DramaFever, and occasionally Hulu, Netflix, and Viki.
For watching/downloading online (with hard subs), I like MyAsianTV and KissAsian. I used to use DramaCool, only because they had a large selection, but I was never very happy with the quality of their vids. I just recently found KissAsian, and they have a huge selection with much better quality vids. They're my new go-to site, and if I can't find what I'm looking for there, then I check MyAsianTV.
For good quality vids with soft subs I used to use Doramax264, but I haven't been able to pull up the site for the past few days. I don't know if they're just having server problems, or if they're gone for good...