@neil There are many Firefox forks which would address these issues such as LibreWolf, GNU Icecat, etc.
But the main issue that one needs to consider is the monopoly of Chromium in the web space. Ditching Firefox for a Chromium-based browser only makes this worse, regardless of the one you choose.
The Chromium monopoly gives Google near-total control over web standards, decreases incentives for cross-browser support (e.g, Skype only works on Chromium-based browsers) and would ultimately leave Google as your last-man-standing with ultimate reign over the web. Not really an ideal scenario, is it?
While these Chromium-based browsers may be ungoogled, hardened and have nice slick UIs etc., switching to them will result in a huge net-loss for everyone in the long term.