had 2 Sierra's, an 09 and a 15. loved both. bought the first new and put 100k on it, only issue I ever had was leaky transmission cooler lines and had to replace the half shaft seals on the front diff. all under warranty, not a big deal either way for both items. the 15 got a new front diff because of bearing noise but I bought it used at 60k and I believe it was a commercial truck in Canada before I got it. maybe a road crew supervisor or something? so could be due to using 4x4 for its whole life. no other issues. I am not easy on it, have towed 7k lbs across the country and max load of boulders out of the mountain's, (could have been over GCVW) sheep over lots of mountain passes, skiing, slide in camper in the mountains and all over Utah etc. I really don't think the quality difference between the f150, the tundra and the GM trucks is very much. I do believe the 5.3 is the best engine out of the 3 and there is nothing wrong with the rest of the GM drive train either. I have 125k on the 15 and don't see any reason to upgrade.
The GM trucks also drive so nice compared to all the others. Easier to drive and more comfortable than a 4 runner, even compared to an outback. My mother in law borrowed my truck, a 6.5 bed crew cab that is just over 21 feet long and she was very intimidated at first. when she came back, she said it was easier to drive and had better visibility than her 4 runner, gets about the same gas mileage too.
Nissan is totally discontinuing the titan, so I really think that should be out. i drove fords working in the oil fields for 12 years. not impressed. my company (a very large company) switched to GM for fleet and has had a huge reduction in maintenance cost on the 1 ton diesels, of which we have hundreds of across the country.
oh yea, Ram... I don't know, they are super nice inside. not much experience with them and FCA builds mostly terrible stuff now.