In response to your questions, mperrywrites
The Jinhao pens... are hit or miss. For a super cheap fountain pen, you get something which works moderately well, comes with a converter, and is questionable on the nib. I don't mean to say they are bad; they just are not consistent. Some are wet, some are dry. That being said, every one I have ever used worked straight away, without me needing to adjust them. But, for the cost of shipping from China (via ebay), you really can't go too badly wrong with these. Also, the scrollwork on the Asian Calligraphy nib is amazing. I shall have to take a pic and post it later.
The Estie... Well, I need to work on mine. I haven't had much chance to use any other ones, but I have to say, for being around 60 odd years old, all I had to do was give it a cleaning and replace the sac, and bam, it worked right as rain. My nib is super scratchy, and that is partly due to how the nib is, and also how I write. The nib shape + my hand writing is just bad. I think if I smooth the nib a bit, it will work well. That said, when I bother to hold the pen and write in the way that the nib works correctly, it is as smooth as butter.
The Sheaffer Prelude has been a workhorse pen for me since I got, being in near constant use for a bit over a year, and I have had next to no problems with it. I will say this- it is a very wet writer. Given the opportunity, I would rather it be a bit more dry. I have Iroshizuku Syo-ro in it now, and the combination of wet ink + wet pen is near disastrous on anything but high quality paper. Still, I love the pen dearly, and I haven't bought a pen since that has knocked it completely out of my rotation. Also, solid metal pen, with a damn nice converter. Super small, compared to my TWSBI 580s, but posted, it is just about right. The metal of the body gives it a good heft, despite its size.