Depends on the nature of the work but I for one don't have extensive collection of specialty stuff. I will buy or make as needed but don't have complete collections of every imaginable version. I like common combination wrenches if possible and the collection of a few that others that have advantages over others for difficult circumstances.
This does include a selection of about 10 Snap-Ons 6 point box in the smaller sizes. After that collection of 3 or 4 sets sockets complete with 6 point in the small sizes with various extensions in 3/8 drive, a couple ratchets and 3/8 air ratchet. 1/2 air gun, ratchet, breaker bar and couple socket sets with extension and then pick off the specialty items as needed, wobbles, etc, usually from auto parts store. I bought 2 sets of 3/8, 6 pieces from after market for 25$ sale flier, ATD, with locking ball on the drive end, wobble. I got a couple in SK too but they really get the use and never had a problem with them. Start using the stuff and go from there.
I tend to find that the longer I wrench the more simple I can get. You need some money in your pocket to buy other things as they come up or I buy on sale, buy starter sets and go from there. Snap ring pliers are a classic example, buy a 50$ set in a box and go from there. All the high use stuff first, Channeloks, vise grips, hammers. Its about impossible to have too much of it. ha