As has been noted, this is a personal preference. And yes, there is a lot of reading as far as pack liner vs pack cover’s go. Fact is, they each have their own set of pro’s & con’s. Ultimately though, as for what you want or use, it comes down to your specific needs & preferences.
Me personally, I use the LiteTrail pack liners that weigh in at 1 oz. This keeps my down items dry on the inside of the pack.
However, I love a front mesh pocket on my pack also, and obviously keep items in it. As a result, I like to also keep those items dry, so I also use a pack cover. Keep in mind though, I am using a pack cover to keep the items in the front pocket dry, as well as a majority of my pack. I don’t expect the pack cover to keep the contents inside totally dry.
I use a large ZPacks cuben pack cover that weighs 1.2 oz, including the stuff sack. I am ok with this weight penalty, considering the benefits it adds.
So, for the pack cover & the liner, the total weight is 2.2 oz, which is less than most pack covers, and even some liners, individually.
If you want something even lighter, the small size ZPacks pack cover is 0.8 oz (including the stuff sack), and the Lite Trail pack liner can be cut shorter, which will drop a little more weight.
Zpacks Pack Cover
LiteTrail Pack Liner