Try some other stuff by those writers if you liked those.
For Garth Ennis try Goddess, its short but pretty good, also, his run on Punisher is probably the best the book has ever been. Reading Preacher, Goddess, and his War Stories stuff made me wish he'd do Punisher, and then BAM, Marvel did the right thing and got him and Steve Dillon(artist on Preacher) to do Punisher.
For Warren Ellis check out Global Frequency, and the first 2 trades of The Authority(you might want to check out his run on Stormwatch before you read The Authority though) Basically its Warren Ellis saying "Why the hell do superheroes only react to things after the fact and only fight supervillains and planetary threats?" So he makes them take down dictators, and god, which is in fact a giant alien organism.
He is also in the middle of a couple series, Fell, which is a series of one shot detective comics in 16 pages. Its kind of an experiment of his. 16 pages of story, with some extras at the end, like the script for the issue, sketches of character designs, etc. Also, Desolation Jones is something that sounds like it would be similar to Transmet in feel. Its about Jones, an ex MI6 operative turned Private Investigator in Los Angeles, which happens to be kind of a retirement home for ex spooks.