Do you have any suggestions of good fountain pens?
I hope I may be allowed to deposit my tuppence worth here, since I have strong views on this.
The fountain pen market is crazy. Really. If you want to spend $1000 there are plenty of options, and no guarantee whatsoever that the product you buy will perform any better than something costing $30. I've yet to hear a single report of a humble Pilot Metropolitan malfunctioning, but there's a certain very prestigious manufacturer which routinely sells pens with skippy nibs, and if you have the temerity to complain, they'll tell you that's how they should be.
Somewhere there's a cut-off point, where you stop paying for writing performance and start getting into the realms of pretty barrels, novel mechanisms and pixie dust, frankly. It's probably around the Lamy 2000 or Pelikan M400 level, both of which can usually be had for something like $150. There are, however, very decent pens available for a lot less, mostly of far Eastern origin. So, if you're a big spender, to some extent pushing the boat out might buy you a better writing experience, but most of the time it'll just buy you bling.
Since this is a calligraphy forum, one assumes that your intention is to use a fountain pen for that purpose at least some of the time. Unless business writing is your thing you'll be wanting to get line variation either with a flexible or broad nib. This being a thread about stubs I'll concentrate on the latter, but suffice it to say that there are no modern flexible nibs on the market
at any price which can compete with old ones made before about 1940, say. There are various threads on the subject: my advice in brief is to start looking for a suitable vintage pen, or else buy cheap and accept the limitations.
There are various different styles of broad nib. You may see them advertised as sharp, crisp, formal or cursive Italic, and also as stubs. The first three versions are generally ground with either sharp or minimally broken corners, giving a crisper appearance to the writing and a more troublesome experience if you have a tendency to twist the pen. Very often they have no durable tipping material on the nib, and need re-sharpening every once in a while. Cursive Italics and stubs are usually tipped and have softer corners, resulting in easier, faster writing and no maintenance issues worth mentioning. A good stub will cost more than a good sharp nib nine times out of ten, and if your intentions are calligraphic you'll get better results with the latter. However, if it's just a case of prettying up your handwriting, those sharp corners are going to be an annoyance, like as not. You can always buy a crisp nib and blunt the corners yourself.
Now for some recommendations. If you want a stub or cursive Italic, many mainstream manufacturers have them available as an option. Kaweco's are unusual in that they're not tipped, but they're nice easy writers. Italix are particularly well regarded, if you can stand a heavy pen (I cannot). You probably won't go far wrong with pretty much anything, but be aware that broad nibs are sometimes susceptible to ink flow issues if the feed isn't adequate: you should be prepared to experiment with different inks if this happens.
Crisp Italics are one of the few genuine bargains in the fountain pen world (and you can always soften them as mentioned above). Have a look at some of Ken Fraser's broad edge exemplars: many of them are written with a fountain pen. The great thing is that these calligraphy pens are invariably priced very reasonably. There's a set by Manuscript which includes half a dozen different nib units which retails in the UK for around £15: add a small sharpening stone at a later date and that will serve you well for a long time. There are slightly more upmarket (but still affordable) options available from Rotring, Lamy, and doubtless some others.
The point I particularly want to get across is that fountain pens are in fashion at the moment and it's big business. There are plenty of people who will tell you that you need to spend $$$ to get a good one, but that's only true if you're interested in fripperies rather than a decent writer. Here, with the benefit of a lot of hindsight, is how I'd spend my money:
Crisp Italic: Manuscript Deluxe Calligraphy set with six nib units - £15
Cursive Italic: Kaweco Classic Sport Calligraphy Pen (choice of four nib widths) - £18
Flexible: scruffy but serviceable vintage Waterman or Mabie Todd - £30 - £50