@BuddyJ expressed some interest. It's a new hobby for me, but I've purchased quite a few and I thought I'd show and tell what I have so far, and give some opinions.
A couple of definitions for those who may not be familiar with fountain pens"
-posting - the act of putting the cap on the non-writing end of the pen
-cartridge converter - for pens that take ink cartridges, a converter fits in the same space and allows you to fill the pen with ink from a bottle.
-nib - the writing tip of the pen. They come in many widths, so for this thread I'll use F=fine, M=medium, B=broad. Typically Japanese pens (Pilot, Sailor, etc.) definition are a full step finer than European/American. So a Japanese M should be approx. European F.
-generally, inks have different flow rates across brands and even colours within a brand. So, if you hate how your pen writes, try a different ink. For example, Pelikan pens are known to flow very well, but their inks are somewhat dry to compensate. Their ink may not work well in a pen that likes more flow, you may find it scratchy and inconsistent.
-nail - a nib that has no flex and likely no line variation. Most modern steel and many gold nibs are like this.
-feed - the black part on the back of the nib, where the ink comes down from the reservoir and 'feeds' the nib
I'm not sure how many pics I can attach to a single thread nor if I can keep them in any sort of order. I'll do what I can, but I'll make a partial list for now.
Noodler's - Flex and Ahab. They essentially have the same very flexible approx medium nib. Very wet writers, lots of ink flow - particularly the Ahab (the fat one), which can be messy to handle, though not on paper. Designed as much for art as for actual writing. Cheap entry level pens, I'd never ever carry one around in my pocket.
Lamy aion M- a new model for Lamy mid 2017. Solid aluminum construction. Cartridges or cartridge converter, which is how I use it. Very very very smooth medium nib (definitely a nail), my favourite to write with at the moment and is my daily user at my desk. However, I HATE that the cap is loose and rattles when on, and takes significant effort to post (put on the back end of the pen while writing), you have to really push it down on the barrel to get a solid fit. As I much prefer to post, I won't carry it around with my - here at home, I've had the cap flop off while writing multiple times, I'd lose it out in the field.
Kaweko Brass Sport M- wanted this for field/pocket carry. Cartridge only, though I believe you can get a small capacity converter. Awful out of the box, reading online tells me many have the same experience but flushing or soaking the pen with a gentle soap & water solution fixes a lot of that - it did for me. I still don't love how it writes, having tried a couple different brand cartridges, but it's at least usable and I will field test it this week. The cap is a little loose posted, which may become an issue if it moves around or pops off - the pen is MUCH to short to use unposted, at least for me. Also to note, online writing suggests the cartridges can come loose, I put a wad of paper towel in the back end of the barrel to prevent this occurence, which is a common hack.
Pilot Metropolitan F - (no pic) cheap entry level, but excellent construction. One of the 3 generally recommended for entry level fountain pens. Cartridges or cartridge converter - it may not come with one, but mine did and they can be had online for cheap. The F nib is way too scratchy and thin for my use, though my wife likes it after I put a better flowing ink in it. I would like to try one in M.
Pilot Namiki Falcon - nib is 14K gold SM = SOFT Medium, allowing for more flex and line variation. Just opened up and inked it today, both my wife and I tried it out. Nice smooth writer for both of us. A strong candidate for a pocket pen when I'm wearing a suit, it has the 'classic' black and gold trim look. Lighter than either of us expected. Posts well. Mid level price range around $150. Pilot is a very well respected fountain pen manufacturer, and this is a commonly recommended 'next level' pen.
Pilot Namiki Silvern Tsumugi M - I am a BIG sucker for sterling silver, this is an all silver body that comes/came in I believe 4 different patterns. I'm going to not ink this one for now, and keep it in 'new in box' condition. I believe the series has been discontinued though you can still find a few new on ebay. Handling it, the body is much smoother than I expected from seeing pictures. Side note, yes it can tarnish over time. For some, what will be part of the beauty of it. I haven't yet investigated, but there are small bags you can get that prevent tarnishing.