In primes, 35mm and 85mm are both SUPER useful in many,many social photography settings. I dunno...I honestly think that for many uses, a regular garden-variety 35mm f/2 prime is the best "value". NO, it's not a Canon 35mm f /1.4-L nor the new Mark-II version of that esteemed lens, nor is it the Sigma 35mm f/1.4 ART...but just a regular, decent,SMALL, unobtrusive 35mm lens. I've owners 2 35/1.4's, and three 35/2's, and one 35/2.8 (all Nikons) over thew past 35 years...of different vintages...late 1960's, mid 1970's, 1980's, 2000's...I have narrowed it down to a 35/2 manual focus with floating element for landscape closeups and a garden-variety 35/2 autofocusing lens... for me the answer is buy the Canon EF 35/2 AND the Canon 85/1.8 EF.
Save money by getting the 35/2, and thus afford the 85/1.8 EF for a reasonable sum, and thus have a really handy 3-prime kit of 35/85/135.
I look at the SMALLER-sized primes as being the better bets for close-range work on people...I do not think that honking, big lenses help people work...I think the smaller, slower aperture, more consumer-ish looking lenses make people feel less invaded upon. Have you seen the SIZE of the Sigma 35 ART? For pointing at people from 7 to 15 feet, that's a bigger lens than I think is helpful on regular people. I feel the same, exact way about 24-70/2.8 and 24-105-L...