Personally, I’d group fountain pens into 4 series-es, with some famous/ classic pens in each as follows:

• Entry level $30 – $60 – Steel nibs, plastic body
  • Lamy Safari
  • Twisbi Echo
• Mid-tier $100 – $300 – Gold nibs
  • Pilot VP
  • Lamy 2000
  • Pelikan M800
  • Rotring 600 (steel, discontinued)
• Expensive pens $400 – $1,000 – Larger size
  • Montblanc 149
  • Visconti Homosapiens
  • Pelikan M1000
  • Conid
  • Graf von Faber-Castell Classic
• Super-Luxury Extra Something Level – $1,500+ – Limited edition, rare
  • Omas Arco
  • Visconti Divina Proporzione
  • Montblanc Hemmingway
  • Namiki / Nakaya Urushi

For inks, I’d say the most famous is Pilot Iroshizuku Kon-peki.

It’s blue, so will be the most mainstream, because people can use it daily even for business writing – it’s a generic standard blue – nice and bright with good shading – many many people seem to love it a lot. Then maybe Sailor Jentle Yama-dori – sheening turquoise. 

For non-standard, Iroshizuku Yama-budo, Noodler’s Apache Sunset/ Golden Brown/ Black Swan in Australian Roses

I just took my pen out of my pocket this morning, and the screw cap which is on the bottom of the pen just came clean off, with no way to screw it on again (it usually acts in a screwing motion, but it moves an inner tube which connects to the large plastic nib+ink+case section of the pen.

There was a slight panic, but nothing looked like it had cracked in half – it is all metal and solid. (I want to use these pens forever – and I’m guessing the first thing that will disintegrate will be the clipping action of the caps… )

It was hard to see what to do – and for the first time I saw the long silver tube which is usually on the inside of the main part of the pen, but this is how I fixed it:

1. Remove the sections: cap, nib, metal tube, main body of pen, little screw nobule which is usually on the top.
2. place the silver inner tube into the body, and then slip the little twist cap onto the end of it
    ~ The way it is held in place is that it is wedged into it, and then the whole mechanism rotates freely inside the body of the pen.
3. put the body of the pen, screw-cap facing down, onto a table, then use a solid long object to apply small, steadily growing amounts of pressure onto the edge of the silver inner tube down into the screw cap – thereby wedging the two into one.
    ~ I was just a bit paranoid of damaging or warping the inner tube, so I didn’t want to just push it down by adding a lot of pressure to one point – so I was working my way around the circumference. 
    ~ When it is wedged together a small amount, you can lift the pen up, and test to see your progress by observing the gap between the screw cap, and small silver section it connects to. The two should be flush together with no gap.

Here is a video of the type of pen I am talking about: