It depends on what features are most important to you. Neoprene is famed for being waterproof and thus easy to wipe clean. Also their hydrophobic properties help it feel breathable if you have just come out of the gym and are a nit in the sweaty side.
Having said that, they are not the most durable which is where canvas seat covers excel. Canvas seat covers will not get damaged easily, and will last for years. The only real downside of them is that they’re maybe not so easy to just wipe clean, although they tend to be machine washable.