Related to the What’s your favourite pencil? thread.
Mine is the uni-ball VISION micro. I like the liquidy look of the ink and the sound the pen makes going across a piece of paper. It also lasts longer than other pens, I’ve found.
So what’s yours?
I have no idea, Even with a magnifying glass I can’t find any identifying marks but I am on to my third refill. It has a soft grip bottom to the barrel and users gel ink.
When I was a kid my favourite was a Parker with a grey barrel. (Still have one, too. 
) Remember the ads? ‘Keep you hands off my Parker!’
Now my favourite is a Levenger Schaeffer fountain pen with a gold and steel fine-point nib. It’s one of their ‘Mediterranian’ series. Aegean? Something like that. It has a translucent blue barrel with gold bands and clip. I use bottled blue ink, sometimes my own mixture of blue and black.
Before I got this pen my favourite was a Waterman Philleas. Its barrel is marbelled blue with gold bands and clip. It’s a nice pen, and reasonably priced. (I think it was like a third the cost of the Levenger.) Only its ‘fine’ nib isn’t as fine as I really like.
Since fountain pens are not suited to some uses I tend to use a Pilot Precise V5 Extra Fine or a Uni-Ball Micro when I can’t use a fountain pen.
Parker Duofold Centennial FP, #21 nib, given me at my college graduation in 1989.
I don’t remember the model name, but it is a Cross fountain pen with a titanium barrel and a 18kt plated nib. I use it for journal entries and general correspondence as well as a weighted placeholder and pointer when reading. For general use I carry a silver Parker retractable ballpoint. It’s a decent pen, and pretty cheap, but sharp looking and a good writer.
I can’t standmost disposable pens; shitty ink and poor tolerance tips that start hemmoraging or binding after the first few pages, but I rather like the Uni-ball Vision Micro pens. I just wish the ink were as waterproof as it claims.
Stranger
Pilot G-2 Gell Ink pen.
I used to have a set of Uni-ball Vision Exact that I loved, but I can’t find them around these parts anymore. I just bought some new Uni-ball Fusions (you know, the gimmicky kind where the ink changes from clear to colored), and I’m really excited to use them once I’m done with my last turquoise Vision.
I prefer the Pilot G2-5
uni-ball GEL IMPACT RT
It’s perfect for doing xwords. Nice broad line and so effortless to use.
Disposable wedge pens are fun, too, when you feel like dabbling in calligraphy
When not FP’ing for one reason or another, my pen of choice is the Uni-ball Deluxe fine point. Very smooth - actually smoother than my Parker rollerball, which tends to skip.
Office Depot medium in red with the gray colored barrel. Bastids stopped making them and I only have three left! In the new white barrelled version the ink color is too bright and just feels wrong.
Lisa, please tell me you don’t write everything in red. Writing in red all the time is sort of like YELLING IN ALL CAPS ON THE INTERNET – it makes people think your every word is a critique.
Pentel EnerGel. Needle Tip, 0.5 mm ball. Smooth-writing, long lasting… what more could you want?
BoD, I use it at work, because it is necessary to distinguish my office notes from the customer’s and client’s on documents. I have only two co-workers who also use red for the same purpose and I’m not much of a letter writer, in case you’re worried I’m offending family and friends! 
Rotring Rapidoliner, 0.18mm. It’s a fine-lined pen that writes on damn near everything, and doesn’t bleed measurably. It’s a technical drawing pen, with all the advantages that implies, but it’s cartridge-based, so it has almost none of the disadvantages. A cartridge, for me, lasts about six months.
Sadly, Sanford bought out Rotring recently and discontinued it. I bought as many cartridges as I could to stave off the inevitable, but for this they have earned my undying hatred.
It depends. For inking pictures, I prefer to use those Japanese Sakura pens of various sizes and weights, according to my needs. For writing, I use a plain BIC 05 pen. The one with the white barrel. I love the smooth way it writes, as I prefer to use a bit more effort in pressing down on the paper.
It used to be the Itoya Paperskater, but when I couldn’t find those anymore, I switched to the Uni-Ball Micro Deluxe. Now those are getting harder to find as well. Maybe I’ll go back to Stabilo, if they still make a decent writing pen. Although I really like the waterproof ink in the Uni-Ball.
Rotring ballpoint. I have one at work and one at home and one in my handbag. Love them.
Either the Pilot G-2 or the Uniball Jetstream.
My regular desk pen is an old Sheaffer fountain cartridge pen, the kind you used to be able to buy at any drugstore, stationary store, or department/discount store. They’ve been discontinued. I still use mine for most of my writing, though. I enjoy the feel of it. I carry some gel pens in my purse. I have a new glass dip pen that I haven’t inked yet. I’m still marvelling over its beauty. I’ll probably use it for drawing and journaling, it depends on how it feels.
I used to love the yellow barrelled “accountant fine” pens for everyday writing. I think that Bic made them, but I haven’t seen one in so long, that I’m not sure any more.
I’m afraid that I shouldn’t be allowed in an office supply store without a chaperone. Those great big rainbows of Sharpies? I grab them. Novelty paper clips? Those are snatched up. I adore miniature staplers, and have quite a collection of them. Most of them don’t work, but I still love them and give them space in my desk drawer.