I've used hemp, bath mats and now fleece liners. I think it comes down to personal preference since all have their pros and cons so I'll share some of my experience as well.
I found the bath mats are most smelly. After a day or two I would already start smelling some pee. The hemp wouldn't start getting smelly for a week or so, but it does have its own smell from the moment you take it out the bag and put it in the cage. It's not unpleasant but it is there. My fleece starts smelling in the high traffic areas after 3-4 days, but I use several smaller liners and pee pads so I don't need to clean out the entire cage each time. I find liners of 2x2 grids in size the easiest to handle and wash, while still having sufficient weight and size that they don't slide around when the piggies run around on them.
The hemp didn't require much spot cleaning. It hides the poos really well. Once I switched to bath mats and fleece I realized how much piggies poo! So the fleece and bath mats require more frequent spot cleaning. On the other hand, cleaning the cage when I was using hemp was more of an effort than with fleece/bath mats since the correx base would get gross where there is a lot of peeing on the hemp bedding. And I needed to sweep the room all the time since the hemp was everywhere after some zoomies and popcorning. So in the end I guess both require about the same amount of time and effort cleaning.