React for 2/3 years, Vue for 1 year building large SASS apps. I use Svelte for my personal site and really enjoyed it, but dismissed it as a contender for my companies latest application. It's community is still too young, there's not enough established, battle-tested libraries for common tasks like routing. It reminds me of React in the early days, I felt overwhelmed with choice and a constant feeling the 3rd party library you are about to go all in with will be shortly replaced with a better, community backed alternative.

I'd love to re-visit that in a couple of years time when it's popularity and community has risen and is more established. Just as React did.

While Svelte is being developed by a great programmer, it's too new, doesn't have all of it's Typescript stuff figured out, and last I checked the unit testing story was still a bit shaky. I'm guessing that in a year or less it'll get those three things figured out.

I really want to use svelte, but I don't know when it'll be production ready. From what I can tell, it's aiming to do a lot more than be a simple js framework. For now, and probably the foreseeable future, vue is good enough. Tbh, the scope for svelte is so large I really wouldn't trust it unless it got really really popular.