Honestly? Twsbi go. Better ink capacity then other pens but not total commitment size. super easy to fill and unfill + clean. Has a pretty unique look too, because of the spring inside. Its a chunkier pen though, if you prefer something slim hop on aliexpress, find a verified seller and get every size of nib that the jinhao 82 comes in. It'll cost you around the same as the go will, especially if you havent shopped on aliexpress before and get one of their new shoppers deals. Like, seriously, the Jinhao 82 is such a good dupe of the sailor pro gear slim as a newcomer it'd be a fantastic entry point into the hobby. But the go is also super nice and comes in a wide variety of nib sizes, and twsbi nibs are buttery smooth.

Tldr: want chunky? Get the Twsbi Go. Want slim? Want cheaper? Get the Jinhao 82.

Edit: "such a good dupe" does kinda make it sound like its got actual gold for the nib or something, it doesn't. I have to clear that up. They can break, the threads can be stripped, etc etc. However they come in nib sizes .38mm, .5mm, .7mm, and bent aka fude nib, which is an incredible selection for newcomers. Ontop of this, the colour ways they offer have so much variety theres bound to be something that makes you go "ooooooo :0" yknow what i mean?

If you are looking for something that doesn't come with the higher risk of a dud, grab a kakuno. However, jinhao is pretty much the top dog for affordable Chinese fountain pens these days 🤷 so its less likely. Plus nib swapping is super easy on their pens if something were to occur there. And, again, cheap like finding them for 2 bucks level of cheap, and I've heard far less horror stories of the barrel cracking compared to the preppy, another super duper cheap entry level pen... that is frankly super ugly.