choose one of these from 18 to 36AWG. they works very well...
https://jokari.de/en/praecisionwirestripper.htm
Another vote for these, especially when doing bulk crimping for Dupont to get the strip length repeatable and correct. It also has a super convenient wire cutting feature. The wire size mm/AWG conversion is written on the tool itself, and the diameter is dialled in on a slider with detents at each of the the marked wire gauges.
The strip length guide slider doesn't have detents, and the minimum guided strip length on the Jokaris is 1.5mm.
There are three basic versions.
PWS-PLUS 001, Mfr# 40024, 26-36 AWG, white thumb push
PWS-PLUS 002, Mfr# 40025, 20-30 AWG, red thumb push
PWS-PLUS 003, Mfr# 40026, 18-28 AWG, blue thumb push
There are also some ESD safe versions for a premium.
Knipex have almost identical tools except for a 30% price hike, the colour, and one key negative difference: the minimum strip when using the guide is 4mm, i.e., too long for Dupont. You can gauge shorter strips manually of course, either by "feel" or chopping off the excess with the integrated cutting feature: this operated with the same thumb lever as the stripper, with its jaws on the bottom of the device.
PWS-PLUS 001 Mfr# 12 80 040, 26-36 AWG
PWS-PLUS 003 Mfr# 12 80 100, 18-28 AWG
CK Tools have this one, but unlike the others I don't have it myself so can't comment in detail other than it's priced between the Jokari and Knipex versions.
Strip-Plus Mfr# 330012, 20-30 AWG
Both the Jokari and Knipex are made in Germany. I don't know about the CK Tools.