Practically speaking, probably nothing that would make up for the loss in functionality. The main practical reasons might be slightly better git support (magit)

Practically speaking, probably nothing that would make up for the loss in functionality. The main practical reasons might be slightly better git support (magit) and the ability to run in a remote terminal -- as well as being generally more lightweight. But for that alone, vim might be a better choice. Conceptually speaking, it remains (despite various flaws and warts) one of very, very few well thought out pieces of non-trivial software. For decades, emacs was pretty much the only program with a search function that didn't suck. Emacs is still the only program I know pf with a decent, branching, undo system and proper, non-alzheimered copy-and-paste. Vim has branching undo system, and a clipboard that can hold more than one item, but both work poorly (e.g. in emacs it's ergonomic to cycle through clipboard history or pull a clipboard item by textual content, in vim it really isn't). Emacs is also remains far more deeply extensible and self documenting than anything else I can think of.