The beta currently has a very limited selection of monster and NPC statistics (understandable since it is a work in progress) -- which others would you like to see added to the final edition of the core rulebook? Ideally there would be a mix of human, daemonic, and xenos enemies to challenge players of all levels. More obscure and possibly sector-specific enemies could be included in a future bestiary supplement, but I feel that the "big ones" should be included with the core game.

IMO, the most glaring omissions in the beta are the servants of Khorne, Slaanesh and Tzeentch. Nurgle is very well represented, and I commend FFG for including a great variety of Nurgle-aligned enemies suitable for players of many levels. I would love to see a similar variety of cultists and daemons aligned with the other Chaos powers in the book (along with some unaligned ones as well).

I think that the core DH should mainly focus on human based heretic enemies. Ranging from gangs to full blown heretic cults. With some small addition of orcs , ruinous powers , corrupted background/role combos. I think a few examples is all it takes for a competent GM to go " I can extrapolate from this and add to it" .

Genestealer Cults. One of the few xenos groups that easily fits into the DH playstyle, and there's a lot of room for variety with them. What I'd like, rather than proper statlines for NPCs, is a set of modifications you apply to any human NPC in the book to make them into a genestealer cultist. As well as stats for the actual genestealers, naturally.

I would love to see the Slaught return - in even more detail than in the DH1 sourcebooks.

I'd like to see a bestiary of creatures akin to the one found in the back of the necromunda 'Oulanders' sourcebook. Just a group of native fauna that could present a risk in a hive or during an exploration.

For the most part I agree that the majority of enemies in DH should be cultists, the game should have a similar feeling to Call of Cthulu in that regard, an actual deamon manifestation should be terrifying (and probably an indication you failed somewhere along the lines...)

Also, I'd be really happy if they added some of the under represented races like the Hrud, the Demiurg or dare I say it the Squats (eaten by tyranids my ass...)

I realise there is probably logistical problems from the IP side for this though.

Demiurg get a big YES

It might be cool to have a Tau empire dedicated splat, expanding at length on the Tau themselves (all castes), their various allied races (including Demiurg, naturally), their technology, how to integrate them into a campaign, etc. Bundle all that with a solid Tau focused adventure and you'd have a decent book.

Hell, you could go the full distance and include rules for Tau PCs. I've always wanted to play a Tau Empire RPG.

This will, of course, never happen. But I can dream!