Funny that, I like pens too
For me, pens are very personal things. What I like may not be the same as what you like. For a start, my pen must be a piston filler. Piston fillers use the entire body of the pen to hold ink, so they last much longer than cartridge fillers. I also like my pens to be light and well balanced, which immediately rules out things like Montegrappa which I find much too heavy for my liking. It needs to be correctly sized for my hand.
Last but not least, it needs to have a superb nib. Nibs tend to vary in quality, some have a bit more flex which may be a good or bad thing depending on your writing style. I tend to write quite lightly, so I prefer more flex.
If you are buying a secondhand or vintage pen, make sure that the rhodium at the tip of the nib is not worn off. If it is gone, the nib will be quite scratchy. The other common problem is dried out rubber (if it is a piston filler), and problems in the feeder (results in poor flow of ink, or leaks). Vintage pens are not everyday writing instruments, unless you happen upon a really good example. I would recommend that you buy new.
As for which pens I like - I don't like any of the pens in current production, except for the Pelikan M1050 and maybe a Mont Blanc 149. I used to like Omas, but that was before they changed their design to be half metal - IMO this made the pen bottom heavy and unbalanced. I used to like Sailor as well (a very underrated brand!!) but newer Sailors are cartridge fillers. As for Mont Blanc - there is something about their obvious branding, their boutiques with their smarmy salespeople and their money grubbing "limited editions" that rubs me up the wrong way. I do admit they make good pens though.
My current daily writer is a Pelikan 1050. It looks understated to the point of boring, but it otherwise ticks all the boxes.