Currently on Rails 3, starting to write unit tests, so is it better to go with Rspec or Minitest given the future of Rails 6 and unit testing?

I need advice. Our software is currently on Rails 3 and we're starting to write unit tests, but we can't decide whether to go with RSpec or Minitest. we're considering to go with RSpec purely over the fact that some of us have experience in it (slight bias included) and that we like the look of it better, syntactically.

But as we're considering future-proofing out software for when we upgrade the Rails versions. As Minitest comes as a default with Rails 5, it seems like the community is turning to Minitest over Rspec for that reason (but not 100% certain if that's the case). With Rails 6 coming in April, it seems all the more reason with go with MiniTest is because new ability to parallel test.

Do you think it's better to go with MiniTest over RSpec, or do you think Rspec will be able to compete with MiniTest still?