My current favorite fountain pen is the Conklin Duraflex (currently loaded with Noodler's 54th Massachusetts). I like it so much, in fact, that I've scored a second one off of eBay (and it will be loaded with Diamine Oxblood).
It's not a super-flex or a wet noodle, but it's got more flex and wetter flow than a Noodler's Ahab. It writes very smoothly and produces nice thick lines with only modest pressure. It has been a joy to use, though I don't use it for everyday writing. It's purpose is really just to be used for calligraphic writing in Elian script.
I've read reviews on Goulet Pens that indicate a wide variability in performance with this model, but I guess I got lucky. Mine, which was from the second round of production, has been simply exquisite to write with. Then again, I'm not a fountain pen snob and my standards are probably a lot lower than most folks.