I don’t have any reference materials to hand as I sit here in the hospital so I’ll just have to depend on memory.
The nib is the heart of the pen. You can have all the admirable filling systems you want, if the nib is so-so then the pen is too.
Which are the best nibs? Your opinion will vary according to how you write and what effect you want to achieve. Personally, I have found De La Rue nibs to be the best. They look rough and unfinished but whether firm or flexible they write wonderfully. After that, I think it would be a dead heat between Swan and Wahl Eversharp. A great deal of their success comes from providing a variety of nib types to suit the customer’s requirements. Strangely, that short-lived firm, Croxley, also provided very good nibs with the occasional real diamond among them.
In general terms, early nibs are better than later ones. If you buy an early 20th-century eyedropper, chances are high that the nib will be fully flexible. Once you get to the forties and fifties flexible nibs are quite a lot less common but they are still around.
One fallacy that is commonly believed is that you can visually spot a flexible nib. I’ve had Swan nibs that had long and tapered tines but were rigid and other stubby nibs that were fully flexible. The only way to know is to try them.
Flexibility isn’t everything, of course. Stubs and obliques are always appreciated. True italics are very rare or completely absent in British pens before the fifties unless they’ve been later reshaped – a wasteful and unnecessary act of vandalism. If you want an italic there are plenty being made today.
What about modern nibs? There are none, so far as I am aware, that have the full and easily attained and controlled flexibility of vintage nibs. That’s not to say there aren’t many good – or better than good – modern nibs around, particularly among Japanese pens. I’m fond of my Platinum 3776 which is a soft fine. Some line variation could be induced but that’s not what I appreciate it for. It touches the paper with some give, making it less tiring on the hand for protracted periods of writing.
No matter what your writing style (or styles) there is a perfect nib for you out there, whether vintage or modern. Finding that nib, though it may take quite a bit of time and money, will be a lot of fun!