Fit is the most important aspect. Sid Mashburn is a good choice. Spending more than a few hundred for an "off the rack" suit from the big department stores makes no sense. Spend the money on a good "made to measure" suit which can be had for about $1500 (most Bespoke starts at $5,000). Also look at the
Divij tour schedule.
Think about 2 good suits rather than a few lesser ones: One dark navy and one charcoal will cover most people for 99% of needs unless you wear one to work every day. Same with shirts, get a few nice ones rather than too many mediocre ones: white x2, light blue x2, stripe, and something fun. Proper Cloth is a good choice, or Mashburn, or Divij. You can get shirts "made to measure" as well. Same for ties (if you plan to wear one), get a few classics/basics that can be matched with the shirts and suits.
And, do not forget good shoes: one black pair and one brown pair should cover 99% of needs. Allen Edmonds is a good basic to start with (only purchase them when on-sale which happens several times a year). Alden is another good option. Carmina is a personal favorite.