I have the bed rug in my 2019, had line-x in my 2018, and wife has line-x in her Silverado - she prefers the line-x (open bed), and I prefer the bed rug (full hard tonneau) - for me, with the tonneau cover, it's like having a full trunk, and I love it - if the bed was open (even though they say it's fine), I'd probably tend towards the line-x.
The ONLY issue I've had with the bed rug is that the adhesive wants to release a bit off the tailgate - so far it hasn't been an issue, but eventually I'll have to add some adhesive to it. I'd still choose it every day of the week, and twice on Sunday. It's SO much easier on my knees. We use my truck for travel, and I use the rear like a "trunk", and it's awesome.
Wife loves the line-x - super durable, and it continues to look great, zero maintenance, etc. Nothing bad to say about it, except that if you have to crawl up in the bed, I'd throw a blanket down or put on knee pads. Excellent traction for your load, or if you're walking around in the back. For bringing stuff home from home depot, or just looking good empty, it can't be beat, and it's awesome.
Bottom line - I don't think you can go wrong with either - I'd choose based on how you're going to use it. I probably would choose the bed rug with a cover, but if I couldn't do a cover because of how I use the truck, I'd go with line-x.
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