Bilsteins are stiffer shock than stock...some like it others dont....you want suspension moving freely and at proper angles....your down travel is reduced, UCA is at bad spot, as well as CV angles.....bigger tires always factor in.......which one or combination thereof is subjective and personal
if you lift an AT4 you need control arms, spacers are notorious for bad ride (travel is limited)...but still it's subjective on what one thinks is acceptable and another doesnt...if you research it a bit you'll have better understanding
When I was getting my truck done a guy with leveled TB broke his control arms along with 2 others I know and numerous threads on readylift AT4/TB level kit gone wrong.....you have (should) to correct geometry when you lift 4 inches.....plain and simple....