Whatever works for you is the best. I believe it depends on how warm your house is, humidity, what enclosure you're using and what heat source you are using.

Eco Earth: Has a nice look, contrasts well with my albino ball python. Helps keep humidity up. I use this with my heat lamp.
Cypress: Also has a nice look, contrasts well with my albino ball python. Helps keep humidity up better than Eco Earth (in my experience). Used with both UTH and lamp. When used in a tub with a uth it made the humidity skyrocket. In a terrarium it was ok since I used a heat lamp+uth.
Aspen: I used this when I kept my snake in a tub. It was great. I would check it every few days as it can mold when it gets wet. I also used this in my snake's terrarium. It was pretty easy to maintain. Had both a UTH and heat lamp. Humidity was a pain to keep up without compromising circulation.
Paper Towels: These are very convenient too if your snake is in a tub. I like to have a double layer. It was pretty convenient to have in a terrarium as well.

I'm switching my ball python to a BAS (bioactive substrate) and I don't like cleaning the cage often. I also like the natural look with live plants. I'm also really into landscaping the terrarium with rocks, branches etc and don't mind keeping track of the live plants. Then again I only have one snake, an albino that would look great in a dark soiled terrarium with green plants and dark decor. It's a weird hobby of mine to do vivariums so that is what's best for me. With my vivarium I'll be using a full spectrum light, UVB bulb (maybe), Night lamp and a CHI (if needed). Anyways it's a lot more work as my house gets cold during the winters. But yeah have fun choosing a substrate!