I have HBO and Showtime, and I've got to say, Showtime is currently FAR surpassing HBO in terms of their original dramatic programming...
Showtime Has:
"Californication" -- Awesome, funny, edgy show starring David Duchovny. Very very good.
"Weeds" -- Some people really love it... I find it just so-so.
"Brotherhood" -- AWESOME. In its 2nd season, truly has the potential to be Sopranos-esque.
"Dexter" -- My new favorite show. A police forensic scientist who is also a serial killer? This show is unlike anything I've seen before and has a great sense of humor about itself while still being a serious drama...
HBO Has:
"Tell Me You Love Me" ... I've watched every episode so far... not because it is some great show... it has managed to keep me interested, however. Deals with four couples in various stages of their lives... probably the biggest storyline right now is one of the couple's struggle to get pregnant through artificial insemination... not exactly edge of your seat type stuff.
"Curb Your Enthusiasm" -- Probably my 2nd favorite show. Larry David is a comedic genius and this season has been great so far... Curb is the one thing keeping HBO on the map right now, in my opinion.
What is really hurting HBO right now is their shows that are on hiatus... Entourage is good and The Wire is another one of my favorite shows.
John From Cincinnati? Cancelled after one season...
Is HBO still the king? Maybe they are, but Showtime has done an amazing job of closing the gap and, for right now anyway, Showtime is the channel that I would keep if I was forced to choose between the two, and it isn't even all that close.