Fountain Pens

For me it started because it was mandatory in first grade, so starting to use them was not my choice. Then I stuck with it because the ink choices were boundless, which wasn't (ans still isn't) feasible with other pens (even if I do re-ink Uniball Deluxe pens with fountain pen inks), that's what kept me using them when I was a kid, and is also something I thoroughly enjoy still to this day.

Then there is the fact that nibs are much smoother, so less fatigue and more enjoyment in using them. Nibs also offer variety in size and shape that can't be matched. Using them, I can write a lot faster, more legibly and for longer.

There is also the less technically relevant aspect of aesthetics. If we overlook the kaküno, preppy and the likes, there is no arguing that they are more satisfying to look at and hold in hand.

I have used them my whole writing life, and even if do occasionally use the odd BIC cristal, or some gel pens, fountain pens are, have been and always will be my main writing instruments. I have around 25-30 inks and 70+ pens, I use around a half liter of black ink per year (I have plenty of other colors, but they see less consistent use, so it's much harder to track), so I can see I use them a LOT, and using disposable pens feels extremely wasteful.

On the rare occasion that I have to use a gel pen for the day, a full refill for a Uniball S207 or comparable pen barely lasts the day, and it can happen that one does not even last the whole day. I do write and sketch a lot for work sometimes, and while these are uncommon examples, they are significant enough that they are a factor in not relying on gel pens... except when I don't have a choice (and I usually pack two spare refills).

Outside of fountain pens, no pen can write the same as a J. Herbin Emeraude de Chivor, that shading and shimmering is just not achievable otherwise. And yes, this is my favorite ink, even if there are plenty I do love. But the breadth of colors and effects achievable for daily writing is just completely out of reach of any other form of pen.

Granted, all that has a cost, not just upfront; but also in terms of finding paper that works with the inks one desires to use. Though, where I live, high quality paper is very affordable (3,50€ for a Rhodia 80 sheets in 90g/m² velum for instance), so I am lucky enough not to have to worry about that aspect.

Edit: typo