1st gen were pretty horrible for the most part, They are the trucks that earned Dodge the reputation of being junk.
2nd gen were good, solid trucks for the most part and would last for years if they were taken care of.....Tons of them still on the road. They put Dodge back on the map.
3rd gen were good, solid trucks as well, My first RAM was an '08 1500 and it was such a good truck that I bought my '15 Longhorn when it came time for a new truck.
I kept my '08 as a second work truck until a couple of months ago when I sold it to a guy that lives near me
4th gen are great trucks and in my opinion are so far superior to Ford and Chevy, that I wouldn't even consider it a fair competition.
I looked at an F-150 King Ranch when I was looking for a new truck and it just seemed completely inferior in every way to the Longhorn as well as being just plain ugly.
I didn't even look at GM trucks because they were so hideous with their big square fender wells, and their ongoing reputation for poor build quality.
5th gen? We'll see, they are probably gonna be great trucks, but they are not much to look at with their new "Lookit me, I'm a Tundra" appearance. The interiors are very nice though, but not nice enough to make me want one.