BEST SAMPLER FOR SDXL?
Having gotten different result than from SD1.5, I tested exhaustively samplers to figure out which sampler to use for SDXL.
Overall, there are 3 broad categories of samplers: Ancestral (those with an "a" in their name), non-ancestral, and SDE.
The ancestral samplers, overall, give out more beautiful results, and seem to be the best.
The non-ancestral ones tend to be more focused on background elements, and can have a lot of details, but are a bit messy on those.
The SDE seem to be the worst overall, showing less details in general, and while not terrible, they just don't shine through anything.
AND THE WINNER IS:
After careful testing, here are the "winners" (according to my artistic taste):
1st Place: DPM++ 2SA Karras @ 70 Steps. This one is artistically beautiful, detailed and typically draws good hands too. If you use one sampler, this is the one. You might want to push the CFG to 7-10+.
2nd Place: DPM Fast @100 Steps Also very good, but it seems to be less consistent. However, sometimes it can just give you some really beautiful results. Works better at lower CFG 5-7.
3rd Place: DPM Adaptive This one is a bit unexpected, but overall it gets proportions and elements better than any other non-ancestral samplers, while also retaining a certain artistic beauty. Also, it figures out on its own the number of steps needed. It seems to work well with quite a wide range of CFG values. Strangely, all the other non-adaptive samplers would give me proportions that are "off" while the DPM Adaptive doesn't have that problem and gives beautiful results.
NOTE: Open the image in another TAB to see it in its entirety.
EDIT: Tested the various "3" samplers. IMO, they don't offer anything better in terms of artistic beauty.
SPECIAL MENTION: Euler a: It used to be my absolute favorite for SD 1.5, but in SDXL tends to create very washed off images. Use only of if you want to create a very dreamy look.