I tend to search my favored genres... Romantic Suspense or Sci-fi Romance or I scroll through friends reviews. I don't have Kindle Unlimited but I do have my library e-lending.
booktok keeps my TBR list unbelievably long. I also like looking up others must read lists. I just found a dark romance one and added a ton to my TBR from it.
Also, how many of you get your books solely from Kindle Unlimited?