There isn't a one size fits all solution for bedliners; the correct bed protection if any depends on how you use the truck.
Drop-ins...
Pros: Inexpensive, usually same-day install, protects bed from dents and dings, easy to slide things in and out of the bed, not permanent.
Cons: Over the rail ones tend to warp over time, may cause fitment issues with other accessories, traps dirt and moisture against the bed so it gets scratched/rusted anyway, if you really work the truck hard you could end up cracking it, stuff slides all over the place when driving.
Spray in...
Pros: Nice finished appearance, surprisingly durable if prepped correctly, generally offered with a lifetime warranty, customizable (spray where you want), actually solves the problem of exposed metal in the bed, flexible and will conform to the sheetmetal if dented, does not impact usability of bed or fitment of other accessories.
Cons: Expensive ($500-$600), can still be chipped/damaged if you put your stuff to work, fades to gray, does not offer as much dent/ding protection as a drop in, some variability in quality.
DIY roll-in...
Pros: WAY cheaper than Line-X or Rhino.
Cons: Does not even approach the level of protection and durability as a professionally done spray-in. Even if you do a really good job, it isn't half the bedliner a professional spray-in is.
Rubber mat...
Pros: Inexpensive, removable, will not tear up the paint, offers some grip.
Cons: Only partial protection, can be easily stolen, sliding things in and out of the bed may be hindered.
I have had two Line-X sprayed trucks. It's a good liner, but they did both fade to dark gray, and I did have some chips and cuts in both after heavy use. My current truck has had a Line-X in it since about '05. It has some small chips and peels here and there, but considering what it has been through, it is holding up well. The bed would be a complete disaster with no paint left without it. Based on my experiences, I think professional spray-ins are the best way to minimize damage to the sheetmetal of the truck bed over a long period of time and hard use.
Line-X and Rhino have different formulations and textures. Line-X tends to be harder (though still pliable), with a finer, but rougher feeling texture if that makes sense. You can still slide things pretty easily on a Line-X, but it's not as slippery as a drop in. Rhino liners are softer with more grip. They feel more rubbery than a Line-X with a "chunkier" texture. Both seem to hold up about as well, but you probably want to check out both before committing to one so that you can pick the texture that works better for you.
The install shop will do the prep for a spray-in, but there is some variability here. IE, some places always take out the bed bolts first, others just spray over them. Check local reviews for the shop you intend to use. That may be more important than choosing Line-X vs. Rhino.
People who complain about rust with spray-ins are probably ignoring the fact that the bottom of the bed is uncoated and all the salt they didn't wash off is what ate the bed. The spray-in can only protect what it is actually covering.
As an alternative, you may want to look at the products offered by Bedrug. In addition to the standard carpet Bedrug, there is now a rubbery one. Just keep in mind that it is possible to steal a Bedrug, and if that happens you are out a few hundred dollars.
Drop-ins...
Pros: Inexpensive, usually same-day install, protects bed from dents and dings, easy to slide things in and out of the bed, not permanent.
Cons: Over the rail ones tend to warp over time, may cause fitment issues with other accessories, traps dirt and moisture against the bed so it gets scratched/rusted anyway, if you really work the truck hard you could end up cracking it, stuff slides all over the place when driving.
Spray in...
Pros: Nice finished appearance, surprisingly durable if prepped correctly, generally offered with a lifetime warranty, customizable (spray where you want), actually solves the problem of exposed metal in the bed, flexible and will conform to the sheetmetal if dented, does not impact usability of bed or fitment of other accessories.
Cons: Expensive ($500-$600), can still be chipped/damaged if you put your stuff to work, fades to gray, does not offer as much dent/ding protection as a drop in, some variability in quality.
DIY roll-in...
Pros: WAY cheaper than Line-X or Rhino.
Cons: Does not even approach the level of protection and durability as a professionally done spray-in. Even if you do a really good job, it isn't half the bedliner a professional spray-in is.
Rubber mat...
Pros: Inexpensive, removable, will not tear up the paint, offers some grip.
Cons: Only partial protection, can be easily stolen, sliding things in and out of the bed may be hindered.
I have had two Line-X sprayed trucks. It's a good liner, but they did both fade to dark gray, and I did have some chips and cuts in both after heavy use. My current truck has had a Line-X in it since about '05. It has some small chips and peels here and there, but considering what it has been through, it is holding up well. The bed would be a complete disaster with no paint left without it. Based on my experiences, I think professional spray-ins are the best way to minimize damage to the sheetmetal of the truck bed over a long period of time and hard use.
Line-X and Rhino have different formulations and textures. Line-X tends to be harder (though still pliable), with a finer, but rougher feeling texture if that makes sense. You can still slide things pretty easily on a Line-X, but it's not as slippery as a drop in. Rhino liners are softer with more grip. They feel more rubbery than a Line-X with a "chunkier" texture. Both seem to hold up about as well, but you probably want to check out both before committing to one so that you can pick the texture that works better for you.
The install shop will do the prep for a spray-in, but there is some variability here. IE, some places always take out the bed bolts first, others just spray over them. Check local reviews for the shop you intend to use. That may be more important than choosing Line-X vs. Rhino.
People who complain about rust with spray-ins are probably ignoring the fact that the bottom of the bed is uncoated and all the salt they didn't wash off is what ate the bed. The spray-in can only protect what it is actually covering.
As an alternative, you may want to look at the products offered by Bedrug. In addition to the standard carpet Bedrug, there is now a rubbery one. Just keep in mind that it is possible to steal a Bedrug, and if that happens you are out a few hundred dollars.
