This is a great thread and I am having similar issues with a simple cotton long sleeve tee and a simple cashmere crew neck.
My experiences...
In cashmere...
Loro Piana is disappointing now. $1K sweater and it pilled after the second wear. They used to be great.
Burberry is a hit or miss. I have several crew necks for $600 each that are perfect. But I bought two this season that were $800 each and both of them started pilling after about 2-3 wears. Also, one has a hole in it already!
So... I am done with expensive brands for cashmere (expensive to me but I know there are far more expensive cashmere brands).
My current brand for cashmere is Equipment, the Sanni Cashmere crewneck, $295. So far so good!
For tees...
Splendid is super soft and lasts. I have tons and they are all holding up great! Tip... they have a 40% off sale that includes their classic 1x1 long sleeve tee, so I stock up then.
Majestic Filatures gives a more dressier tee shirt look. I size up as they are cut a bit slim to me. I also love their soft jackets. My favorite is the striped jacket for summer... with a tee and skinny jeans. Their 100% cashmere also seems to be great. I purchased a sweater this season and so far so good! I am impressed with this brand. Bloomies offers 25% discount often.
Vince is average. I love the Pima cotton but it’s on the sheer side and I get tiny holes at the waist so I think the quality is not good.
Saint James for cotton stripe tees. They are made in France and last forever. I also love their stripe combos!