I really noticed mine were bad on the highway. Almost felt (and sounded) like I was leaving the road on occasion. Tire noise would fade/increase. And the side-to-side roll was quite dramatic.
I replaced the stock ones at about 75000 miles and felt a huge difference. Truck felt solid again. Got Monroe Reflex shocks because of lifetime warranty. NOw, every 30k I take them out and run to the local auto parts store to swap them out.
I thought about Rancho, but the lifetime warranty on Monroe was a big plus for me. And since I do mostly road driving now
, they were the best value. Billstein and Edlebrock were a bit more than I wanted to spend, and no lifetime warranty.