It really depends on what you want to do and how familiar you are with JavaScript. NextJS is a React Meta Framework, meaning it’s a super set of React. If you just want to get started with React style virtual dom programming, react, preact, vue are all good choices. Directly start next without basic react understanding might give you more trouble down the line. I recommend to start with a simpler, smaller tool chain.
Discussion
That's why I'm asking :) I'm really into backend and DevOps but not into Frontend. Any recommendations? I'm familiar with vanilla JavaScript a bit and already did pollstr.online in vanilla JS. But I want to use the npm package nostr-tools properly also :p
Just start with plain old react is the simplest thing.