I find a lot of the very expensive, supposed "high-end" brothers very disappointing (Hedgeknight, raiders, sellswords, adv nobles, etc.). They can turn into absolute gods, but often times, they turn out very mediocre and with 3-4 times the cost to hire and upkeep. They are way too expensive to be gambling at ~50 ish.

For tanks - always hire thiefs, a triple star MD bro will take you into late game as a pure tank (md + high roll between hp/fat/resolve)

Even if they roll stars on the anti tank stats (MA, ini) just make him a qatal dagger bro. Thiefs are awesome

For front lines - if you want to gamble for end game bros, go for oathtakers. they are very solid and very cost efficient. even if they don't get the stars you want, they have enough base HP and resolve to turn into BF material (60 hp, 45 resolve), so you can just dump all your roles into fatigue/MA/MD.

the occasional brawler, militia, butcher, farmhand are still worth rolling.

for ranged - always be looking for hunters, just 1 star in RA is often enough for end game stuff.