That's funny, I just did this on Friday! I used Harvard Business Services, URL delawareinc.com, which is not on your list. After reading about a dozen of these sites, they seemed really credible and I liked their tone and demeanor. Bonus: their registered agent pricing is the lowest I'd seen at $50/yr.
It's now Wednesday, and they just emailed me PDFs showing that my company has been formed and everything has been filed with the state of Delaware and the IRS. I'll get hardcopies of everything by next week. You can pay more to have the stuff mailed faster, but this is pretty good as far as I'm concerned. I started the process on their website on Friday night. On Tuesday they emailed me an IRS form to print, sign, and fax back, which I took care of right away. Today I already have a Delaware LLC with an EIN. Not bad at all for $400 total.
