Are These Publishing Services Really as Good as They ClaimI

I keep seeing lists online claiming to rank the best self publishing companies, but it’s hard to tell which ones are genuinely reputable and which are just marketing themselves aggressively. Some offer full-service packages, while others seem vague about what you actually get for the price. How do authors figure out which companies truly deliver value and which might be overpromising? Has anyone here had real, firsthand success with any of them?