I wish there was an edit button for older posts: I meant to qualify that. The actual pragmatic quality may be higher (particularly re terrific speed optimisations, with bitmasks etc), but the cleanness and readability I feel has dropped (some due to extreme modularisation, which is v useful but makes reading source painful). There aren't as many comments, which seems kinda minor except in the context of Jeremy Ashkenas' attempts at literate programming, esp via Docco, which IMO was fairly successful. I still use Underscore source and docs as reference. LoDash I find has pretty awful docs in terms of how they're arranged vs Underscore, but that could just be due to experience.

Lodash source is available as a monolithic build or modules so you can take your pick.

Lodash has plenty of comments (jsdoc, bug fix notes, and implementation explanations). Underscore has stripped many of these leading to devs making the same mistakes or introducing regressions.

Lodash docs are arranged in alphabetic order. Underscore docs aren't and even have thing miscategorized.