A cat that recently started eating litter probably should be checked over by a vet. It could be some health issue, up to and including a nutritional/vitamin/mineral deficiency. 8yo is heading into senior hood and that is usually when health problems can begin.
By all means, let's get a vet check. Especially at his age. And, even if everything is normal, you have a good baseline should he get sick later! I consider a senior wellness check to be essential when a cat reaches that age, and should be done annually. Then more often as they age. Just because.
That said, IF there are no health issues, then we can explore the options. While my girl was addicted to corn cob litter (and did not eat it), I've heard several members speak very highly of Yesterday's News, a recycled paper litter.
There are many different pellet litters and some are easier to clean than others. It also depends on how you like to clean. I don't like clumping agents because it sticks to the sides, so i tend to like the pellets that get darker and I scoop them out and dump the entire box weekly.
Some people prefer the pellets that puff up and dissolve.
There's prefer the regular pellets.
There's some litters that work better in different environments as well. for example Naturally Fresh walnut shell litter does not work well if your climate is naturally humid. I like in a humid place in Canada and the litter moulds overnight after they poo on it in the basement. Upstairs it moulds in the winter. Anyways we stopped using that one.