I moved to Paris from another EU country a few years ago. Paris would meet your "good transit and quality of life" criteria, I think. Given sufficient pay, that is.
As for fluency, here you definitely need basic French outside your work for taking care of basic things like getting health insurance, filing your taxes, getting Internet, etc. You might find jobs where English is the working language, though I believe they are rare. Where English is not the working language, in my experience French colleagues do not like switching to English. So it's hard at first, although people are also very accommodating if they see that you have basic knowledge and are trying to improve. From my experience with other expats who did not want to learn French, they were not exactly welcomed with open arms, and they weren't happy here.
Things are very probably different in other places. Scandinavia is said to be more English-friendly. And then there are Ireland and Malta with English as (an) official language. Ireland especially has a lot of tech company presence.
I'd say that if you're willing to put in some effort into learning a language, go for it!