I have been interested in reading comics featuring Namor and I was wondering which Namor comics are considered as the best?
I'm also interested in reading the "Namor: The First Mutant" series that was written by Stuart Moore and John Byrne's Namor series.
A lot depends on what kind of stories and writers you like. There ARE 75 years of Namor stories to chose from, and that covers a wide variety of styles and tastes.
I love the late Silver Age / early Bronze Age books, and my favorite Namor run is probably Roy Thomas' with John Buscema, Marie Severin, and Sal Buscema. So, my own personal favorite to recommend to folks unfamiliar with Namor is the SAGA OF THE SUB-MARINER. It's a 12 issue mini-series that covers Namor's entire life from his parents meeting to the death of his second wife, right before John Byrne's 1990s run. And the best part, is it's autobiographical. Yes, it's told entirely from Namor's PoV, because he's writing his life story! It's actually written by Roy Thomas (one of my favorite Namor writers) and lushly drawn by Rich Buckler with inks by Bob McCleod. The only negative, IMO, is Buckler draws Namor with a very very flat top hair cut. If you don't feel like tracking down the issues, you are in luck. Marvel is releasing a trade collecting the mini-series, in the fall.
Lots of people like Byrne's Namor series; it has an intriguing premise -- Namor as a CEO of a green company. I have some issues with it, but over all it's solid work, with a more straight forward, hero mode, Namor. It mostly takes place out of Atlantis.
For a modern take on Namor, yes, the Stuart Moore NAMOR THE FIRST MUTANT series is good, as it gives you an idea of what motivates Namor, which you don't get in any team book, presently. It mostly takes place in Atlantis. The big negative is the art. It's a merry go around of disparate artists and inkers, sometimes two or three on a single issue!
If you want to see what brought Namor to the Cabal and the X-Men, then I recommend SUB-MARINER REVOLUTION. It's a mini-series that's been collected in trade, that takes place in Atlantis and on the surface, post Civil War. It's something a thriller / team up, as Namor visits various allies to help him deal with rogue Atlantean terrorists, while Atlantis is being threatened by SHIELD. It has a great final page.
SUB-MARINER THE DEPTHS is an excellent story, but it's not that good of an intro to Namor. First off, it's an alternate universe, and second, he barely appears on the page in the mini-series.
And then there's the Golden Age ... but if you are a GA fan, than I'm betting you've already read Namor, as he was one of Timely's biggest sellers.
Team books, like Defenders, Invaders, Avengers, X-Men,Fantastic Four, etc. are nice appetizers, but they rarely give you the full meal, when it comes to Namor. Read a story where he's the focus.