I got this! The Dark-Hunter universe is a bit of a beast because Sherrilyn Kenyon started weaving in the Dream-Hunter and Were-Hunter arcs pretty early, and then later added the Hellchaser and Chronicles of Nick stuff. It's not just one straight line.
For the core Dark-Hunter books, publication order is the safest route to avoid spoilers. Start with 'Fantasy Lover' (Julian's story), then 'Night Pleasures' (Kyrian), 'Night Embrace' (Talon), and so on. That's how most of us long-time fans experienced it, and the overarching plot about Artemis, Acheron, and the Daimons unfolds in that sequence.
Where it gets messy is when you hit books like 'Upon the Midnight Clear' (Dream-Hunter) or 'Bad Moon Rising' (Were-Hunter). They're set in the same world and characters crossover. I'd say stick them in at their publication point. Trying to read all the Dark-Hunter books first, then all the Dream-Hunter books, will leave you confused because major events in one series impact the others. The timeline is interlocked.
Honestly, my first read-through I skipped the Dream-Hunter books and was totally lost when certain characters showed up later with all this backstory I'd missed. Had to go back and fill in the gaps. The official website used to have a combined chronological list, but even that's tricky because some books have flashbacks to ancient Greece.