Depends how much he and you would like to spend and budget.
If budget no option go Joseph with Paul Smith, Hugo Boss, Prada etc. add in Pringle and other 'Jermyn Street' posh brands.
DB wears a lot of Belstaff, Zara, Fat Face, Cos etc.
My boyfriend has a lot of older clothes but his boss buys him e.g. Daks coats and he has some lovely handmade coats but also likes Anthropologie for men and Arket mixed in with designer bits here and there plus Oliver Sweeney and Reiss.
For casual bits it can be anything from Patagonia to Joules to vintage sportswear.
Shoes - again trainers but they vary so much from Veja, NB, adidas, classic Churches shoes etc but DMs or Clarks are good for basics.
Agreed with someone that men need to spend more as they get older and I've been told that quality in mens clothes you need to pay more.
Ex BF used to love a brand called Uth which was an offshoot of Jigsaw menswear and said H&M (back in 2000s) had good menswear if you looked.
Levis jeans are a standby for men but DB's fave trousers were from H&M.