Fast, not really something that comes up for business laptops these days. Most business class software will run on pretty much anything.
Thinkpads are a good choice for larger companies as they have all kinds of IT related features like VPro chips and BitLocker support. They are actually quite expensive.
We piloted a few Carbon X1 here and they were quite good. Ended up with a bulk purchase from Dell though. (Actually second choice, the finance people insisted on a cheaper HP, if they had been able to deliver we would have had them instead)
Latitude E7440 are what we ended up with. Dell installed Lite-on SSDs in all of them.
For a small business any laptop with an i5 u class processor with 4-8GB of memory is all that is really...