Which camp do you fall into? Of course, this refers to fountain pens. If you have to clean ink out of your rollerball, ballpoint, or gel pen, it's probably because something very, very bad happened. But pen maintenance is an essential part of fountain pen ownership. You have to do it, and to the extent you can, you should learn to love it. Do I? Sort of.
Pen cleaning is one of those things people do either (1) all the time, such as, after they finish every fill of ink; (2) semi-regularly, such as whenever they change colors or every 1-2 months; or (3) whenever the pen clogs up and stops writing. I'm squarely in the second category. I don't find cleaning pens to be torture, per se (unless it's one of the rare occasions I've been using some sort of Noodler's permanent ink), but it's not something I necessarily look forward to.
I'll walk through the various categories of pens that I clean on a regular basis, from what I consider to be the least difficult to the extremely aggravating, and provide my perspective on which of the various filling systems are easiest to maintain. While the basic principle is the same for all--flush the pen with water--each system has its own peculiarities and quirks that need to be taken into account.
Syringe Fillers. Say what you will about Conid's Bulkfiller system being hard to get the hang of. Once you do, these pens are a snap to clean. It's like using a built-in bulb syringe (see below). Because the pen has such a large ink capacity, it's capable of pushing a large amount of water through the nib, reducing the number of times you have to flush it. If the pen's clogged, or if you've used an ink that's extremely difficult to clean out, you may have to disassemble the pen, but most syringe fillers have a small number of moving parts, and Conid even provides you with tools and instructions.
Cartridge/Converter. I have a growing appreciation for cartridge/converter pens because of how simple it is to clean and maintain them. While you technically don't need any special equipment, and can just use the converter to flush water through the feed and section several times, a bulb syringe and an ultrasonic cleaner allow you to thoroughly clean your pen quickly. For me, one of the best features of the cartridge/converter system is that you don't actually have to worry about cleaning the entire pen. Typically, the only part of the pen that touches any ink is the nib section and the converter (though I would recommend occasionally cleaning out the interior of the cap).
Eyedropper. Some people are going to be puzzled at this one. How, they might ask, is an eyedropper filling system--where the entire barrel holds ink--more convenient than the piston filler? Because there are no moving parts, and all you have to do is drop the entire pen into the ultrasonic cleaner. (In the "after" photo below, there is still some blue-black residue in the barrel, which I will clean out with a q-tip if I decide to change colors.) While disassembling a pen takes time, you don't have to do it that often! Eyedroppers hold a ton of ink, and if you use a low-maintenance ink and don't feel compelled to change colors, well, you can go a long time without cleaning that pen!
Piston Filler. Some piston-filling pens are easier than others to clean. Pilot's Custom Heritage 92 is a snap (because the piston is highly efficient and works well), and the clear TWSBI demonstrators are also somewhat convenient because they are transparent and relatively easy to disassemble if necessary. At the end of the day, however most piston-filling pens simply take a long time to flush out all the ink, and I often worry whether that repeated flushing is good for the piston mechanism. I've had particular difficulty cleaning my Montblanc 146 and my Pelikan M600, though the otherwise excellent Lamy 2000 can be a pain as well. On all three, I've noticed that the piston mechanisms have loosened up over time, after many many cleanings.
Pilot's excellent Custom Heritage 92 is extremely easy to clean. The piston is highly efficient, and as you can sort of see from this terrible photo, the piston fills the ink chamber to capacity, making it easier to flush out the pen.
Sac-Filling Pens (Lever and button Fillers). Flush these pens with water until it runs clear. I have these pens listed pretty far down on the convenience list because sacs tend to accumulate ink residue inside them, and it's generally impossible to have any visibility into what's going on inside the pen because they aren't made to be disassembled on a regular basis. I very rarely use anything other than a "safe" blue or black ink in a pen that fills using a sac.
Vac-Fillers. And then, we come to the end. I love the mechanics of a good vac-filling system, whether it be the classic Parker Vacumatic and the Edison Menlo. I absolutely hate cleaning them. After much experimentation, I have scientifically determined that it is physically impossible to get all of the ink residue out of a Parker Vacumatic. No, not really, but it takes so long, and involves so much repeated filling/emptying the pen with water, that I've given up on regularly changing the inks that I use in these pens and stick to "safe blue" or "safe black". To illustrate how much effort (and ingenuity) it takes to clean these things thoroughly, check out this article by Ron Zorn, who built a centrifuge out of a salad spinner. (Yes, really.) In all fairness, the Vacumatic filling system is the product of a time period when most people used three colors of ink (blue, black, and blue/black), so this probably wasn't an issue back then. (See note below: a "vac-fill" pen is a pump filler, distinct from the "vacuum-fillers" made by TWSBI and Pilot. For a demonstration on how a "vac-fill" pen works, see Brian Gray's video.)
As you can probably tell, this post isn't intended to be a comprehensive, "how-to" guide on cleaning pens (though that may not be a bad idea in the future). I mainly wanted to provide my thoughts on how easy/difficult I've found certain filling systems to maintain, since it's such an important part of pen ownership. Opinions may differ. But if I could provide you with one "semi-pro tip", it would be:
Buy An Ultrasonic Cleaner. I was once a skeptic, but about a year ago I purchased one at Bed, Bath & Beyond on a lark and I've since become a convert. You can get these things really cheap (even cheaper if you have one of those ubiquitous BBB 20% off coupons). The ultrasonic cleaner is great for cleaning ink out of the nooks and crannies of feeds and nib sections, and saves your fingers a lot of repeated flushing. If you use a lot of red ink, like I do, the ultrasonic is a lifesaver, because reds can be notoriously difficult to flush.
Note: I don't have a ton of experience with vacuum-fillers such as the Pilot Custom 823, TWSBI Vac 700, or the TWSBI Vac Mini, at least not yet. I've recently picked up a Vac Mini, and plan on having my thoughts on the pen up on the blog soon. I expect that in terms of ease-of-cleaning, these pens will probably fall somewhere between a piston filler and a vac-fill.