React Native. Not because of the framework, because they both work well, but hiring a JS dev is about a billion times easier than hiring a Dart dev so if you need someone to support you later things will go much better.
I dabbled with Dart for sometime, got an impression that a competent Java/C# developer can pick up Dart in no time, I think hiring shouldn't be an issue.
There are a bunch of problems. Firstly, people simply don't apply for jobs that use languages they don't know. That makes filling a role really hard. Secondly, if someone has to learn the language when they join that puts a lag on how quickly they can be useful. You can't go as fast, which is bad if you're a startup. And lastly, companies are (usually) very reluctant to let someone spend the first few months getting up to speed if a technology choice means they can recruit people who'll immediately be effective.
That's not to say using a less popular language is a bad idea (it isn't), just that hiring should be a part of the technology decision making process.
> Firstly, people simply don't apply for jobs that use languages they don't know.
I did in my last job change - and 80% of the office here didn't know the stack/language when they first came in.
> Secondly, if someone has to learn the language when they join that puts a lag on how quickly they can be useful.
You could learn enough dart to be useful in a day if you are a C#/Java dev with JS experience - enough to go through the codebase - and thats something that takes time no matter what the language - dart isn't that exotic.
Flutter has a higher learning curve but that should also be on the order of week or two depending on how much you know about frontend. React native is the same deal.
> And lastly, companies are (usually) very reluctant to let someone spend the first few months getting up to speed if a technology choice means they can recruit people who'll immediately be effective.
Meh - when they chose stuff like Dart they know hiring pool is limited and usually word the job posting like that - ie. they expect you to be able to pick it up on the go.
I mean your whole argument is nonsense because things like this happen all the time - my current gig I started as a .NET dev with some python/django experience - I'm working on ruby on Rails stack - never touched that before in my life. Took me like 1 day of reading up to be able to go through the codebase - a few weeks and code reviews and I'm pretty much in tune with how they write RoR.
>Firstly, people simply don't apply for jobs that use languages they don't know.
That could be because experience with that language is often listed as a requirement.
>someone spend the first few months getting up to speed
In my opinion, "few months" is a huge overestimation, if we're talking about an otherwise experienced mobile developer who understands the underlying platforms (Android, iOS) well. A few weeks should be enough to get up to like 90% of their usual productivity (ballpark guess).