VueJS or ReactJS

There's no simple answer to that question, as it really depends on what you need. Do you want to find a job in a front-end field? Then bet on React as it has bigger community and ecosystem, hence there's a bigger chance to land a job. Do you care about performance? Then choose Vue, it's smaller and faster, also I personally think it's more fun to work with. Try both and decide yourself. 👍

What about Svelte?

React is harder to work with imo, there's a lot of information that you have to learn where vue can let you get away with more and not have to know why something does or doesn't work.

After react 19 and they release their compiler it might be more equal in that regard.

I have heard that between Vue, React and Angular the easiest one is Vue followed by React, and Angular is the hardest one.
Personally, I would like to use the easiest one which is Vue but I will try React too. I do not know for Svelte.
I do not think I need to know all of them.

Personally, I prefer Vue. However React has a larger ecosystem.

React has the biggest market demand - Vue is faster and easier to write.

You should try both, that's the best way to understand the differences and make your ourn decision about.

If you need to pick one for you job, then I think there is not so big diffierence. Just check out what is known in your company.

If you're self-employed, then consider the market, what will be more attractive for your clients?

That's just my thoguts.

Parroting a lot of the same answers, what's your goal?
Work, React has he most reach right now. That isn't to say that you can't land a role with Vue, but the number of opportunities will be far fewer than React. That doesnt change that the competition for the role exists just the same, but there will likely be less qualified applicants as well.
For fun/personal? Vue is really nice to work with, same with Svelte. I find they're written and running quicker and I've rarely found a pitfall to either versus React.
The one that React really does have going for it, besides the number of positions available, is the ecosystem around it. Tons of ways to accomplish the same thing with ease. If you have a problem, someone's probably already came up with a solution that you can find easily. With Vue and Svelte, it can be a bit harder to find the answer, and sometimes the question has never existed to be answered so you may have to be the one to ask it or find the solution yourself.

Learn basic HTML, CSS and Javascript first and master those. The others are just nice to haves. But on that, it depends on why you want to "study", for more job opportunities it still seems that React is king in this, but so is Angular. On that note why not learn both? You can also widen your horizon and look at React, React itself, and Next.js. And on the Vue side, do Vue and Nuxt.js. These will let you see a lot of differences. But you can also expand your horizons with plenty more Javascript frameworks like good old JQuery, Svelte, Knockout, Ember, backbone, mithril, polymer, inferno, solid and plenty more out there. Each have their own strengths and weaknesses to look at. Some are simple additions to the basic html+css+js and some others are pretty advanced and quirky like Qwik, riot.js or Aurelia.

What's most important is the why then you can prep yourself for your journey

I use both, when I write react I don't get as much pleasure and fast results as when I write vue, I have used vue in many projects from big to small and I have seen that it meets every need easily and vue.js supports both jsx and html templates, but if you want easier business opportunities, you should write react because its ecosystem and business opportunities are unfortunately more than vue, so it has a lot of libraries, but vue is not far behind in this regard, if your basic javascript knowledge is good, after learning one, you can learn the other with a little effort.