For TST in Chrome I've been very happy with Tabs Outliner (https://chrome.google.com/webstore/detail/tabs-outliner/eggk...).
As well as a great tree, you can mix live tabs/windows with frozen ones that don't consume RAM, and this is all reliably persisted across restarts.
Tabs Outliner is a separate window, since Chrome extensions can't add sidebars, so rather than using it as a tabbar replacement I tend to have multiple windows with less than 10 tabs, and open Tabs Outliner when I want a coherent overview (e.g. to quickly skim through my tab titles before closing them in bulk).
Tabs Outliner is a separate window, since Chrome extensions can't add sidebars, so rather than using it as a tabbar replacement I tend to have multiple windows with less than 10 tabs, and open Tabs Outliner when I want a coherent overview (e.g. to quickly skim through my tab titles before closing them in bulk).