Separate process tabs? Rendering and javascript speed? UI features? I know it's popular on HN to focus on technical features, but that entirely misses the point of this post.
Technical features will continue to improve over time. The browser that is "best" in any given area will change as the code evolves. Most of the other reasons to like a given browser are the subjective opinions we all have or the particular use cases we have in mind.
None of this matters. When comparing Firefox and Chrome, the substantive difference isn't which browser is faster or which browser uses less memory. The difference that matters is the power of monopoly and what their dominance means for our future. Supporting Chrome by using it is a vote in support of Google being able to dictate standards. Chrome already sends way too much data[1] for storage[2] and analysis.
Even worse, using Chrome instead of Firefox will eventually damage the Free Software[3] ecosystem. While most people focus one the availability of source code, barriers in interoperability is the more fastest and most effective way restrict both developer and user freedom. This is why the LGPLv2 puts a special restriction on static linking; you (usually) can't replace or modify the Free Software components unless they are dynamically linked[4]. We already see Google following Apple's lead in restricting phones. Do you really want the browser to end up with Android-style limitations[5]?
Even though I don't think it's a good idea to let anybody aggregate and analyze all the data we generate, I can respect the decision of someone who actually wants Google/Chrome to win over Firefox. I'm primarily suggesting that there are Big Issues going on around us and - intentional or not - there seems to be a lot of people being distracted by stuff that won't matter in the long run.
"...we have to create the future, or others would do it for us."
- Ivonova, B5/"Sleeping In Light"
[1] Firefox has problems here as well, unfortunately.
[2] Even if Prism and XKeyScore didn't exist, that data is still merely a subpoena or "national security letter" away from the NSA or any other branch of government.
[3] "Open Source" is not the same thing.
[4] (lack of) interoperability is also the problem a lot of us have with systemd. Too much focus on technical features that distracts from the threat to interoperability.
[5] https://www.gnu.org/philosophy/android-and-users-freedom.htm...