For a free offering, Daz' Iray is excellent and the version embedded with 4.12 beta is going to be optimized for use with RTX cards for even more stellar performance (especially real-time):
You must be registered to see the links
Iray relies upon MDL materials (i.e., derived by NVidia for their own products) so other renderers typically need some form of mapping to at least give you an approximate start on setting up equivalent shaders (using a different specification or shader) in their systems. The nice thing about Daz' Iray is that comes for free. For me, their material node system can be less flexible or at least accessible in daily use and is somewhat clunky (totally subjective opinion here - coming from a person who has worked with node systems for Poser, Blender and Autodesk-shipped renderers, plus V-Ray.) In the end, you can still get render layers (using a different NVidia convention, but same concept) and other needs from Iray in Daz, which is pretty cool.
Octane is probably the next closest render integration solution for Daz (and Poser) scenes, at least from the perspective of launching from within the UI, having its own pane in Daz and even its material+rendering details saved as part of your .duf file (i.e., OTOY extends the standard .duf format with additional data). It also does standard approximations of 3DL and Iray-oriented Daz shaders to Octane materials on-the-fly and on-demand, at the Daz "surface" level. It usually gets you about 40-75% of the way there after the first pass, in my experience.
So, you need to tweak for optimal Octane material and lighting use in most cases but much of that is sped up by relying on a combination of Octane's user-submitted material library, your own material library or those you can purchase. After that, it's a simple matter of drag and drop onto a surface to get that leather couch look you previously liked for a different model, then easily go in and change the color, specular settings, etc. to make it a new variation on the theme (then maybe save that to your personal material library, too.) Its node system becomes second nature after trying it for only a little bit and experimentation yields real-time results so there's no waiting to try out all sorts of ideas on-the-fly.
If you wanted to try Arnold, Redshift or other renderers, their integration would be in the form of exporting your objects or scenes from Daz in FBX, OBJ or similar format and then re-mapping in the app supporting those renderers and then working on them uniquely outside of Daz at that point. I don't think any of them handle Iray's MDL shaders natively, unfortunately. The export process is generally easy, but the Daz to Maya product makes it a couple of clicks and makes the choices easier:
You must be registered to see the links
. That said, the entire reason I went for Octane was to find an integrated, real-time PBR approach which worked for Poser and later for Daz, actually.
Honestly, if you were going to try the export and eventually render route, you might also consider Blender because Cycles is pretty decent and its nodes are super-flexible, IMHO. Plus, it can add hair, physics, etc. that the big Autodesk and Maxon products offer in a free, pretty capable all-in-one package. It has the ability to import morphs and bones from Daz with an add-on (to an extent) as well, so you can even pose after importing an exported Daz scene. I've also used a Maya-to-Blender transformation utility and that worked great, too - Blender is just fun as a barrel of monkeys, IMHO. I realize you've been looking into Maya and it does beat out most packages in the animation department, corporate workflow areas, etc. (which is possibly where the Arnold influence came to you, I am guessing).
I still use Iray! It's very good at simply using things out of the box, though it still needs at least some tweaking in the shaders and render settings to get what I need. If that takes too long for a quickie scene that I thought would be best with Iray's qualities, then I will go to Octane because I can tweak there so much faster.
Here's an example where the scene was comprised of objects with materials for Iray, 3DL and Poser Firefly renderers but didn't work well for all of them, so I went to Octane as the common ground and got most of what I needed after about 10-15 minutes of tweaking (and longer for fine-tuning, primarily trying for early morning lighting in a weird space):
https://f95zone.to/threads/the-visit-v0-10-fix2-stiglet.10361/page-163#post-2103541
I could have done the same thing with Iray shaders, btw - at least for my style, it would have taken me longer. But, perhaps for you that would be a much shorter period of time to get the setup you needed.
As mentioned, it's possible Daz 4.12 with RTX cards will further enable Iray for real-time draft performance when that's delivered.