I never understood the ecosystem argument as applied to Svelte. Vanilla js libraries integrate with it pretty much perfectly, meaning you don't need a Svelte port of a given library. The ecosystem is effectively huge.
There aren't very many good modern, maintained vanilla js libraries. But for just about anything I need in React I can find something polished and well supported that just works.
I'm not sure I understand. What types of libraries? When I think of libraries, I think of ExpressJS, lodash, JQuery, left-pad, etc. There are absolute tonnes of vanilla JS libraries.
I've rarely used React, are you talking about React-specific libraries? I find it hard to believe that there are more maintained React libraries than vanilla JS libraries.
I don't have a strong opinion on the whole, but as someone who's been building a diagramming app for 2+ years, I've found react-flow to be the most solid free & open-source node-based diagram component, by far. At least in terms of quantity/quality of features and UX/DX. Though admittedly I haven't thoroughly looked at alternatives in about a year.
It basically singlehandedly convinced me that the ecosystem was worth going with react when I started my project, despite really enjoying svelte.
All those libraries also work in React of course. The only vanilla js libraries that don't work well with React are UI libraries that assume they can control the DOM. But I can't think of many of those I'd prefer to the many excellent React UI libraries.
