I agree that the 'pro' spokey is slightly worse vs nipple kinks and that the DT design (which is similar to the 'Unior' one in fact) looks good from that POV. However the metal end may more easily scratch rims. I try to avoid building wheels with big kinks at the nipple, because it can cause all kinds of problems. This type of key
might be OK but I have not used one so sizing or quality may be poor.
BTW I did try a ('Fat Spanner', four-size) spoke key
with a different slot design, in which the slot had all four corners present and entry was in the middle of a flat face. You need to slip the key over the spoke and slide it upwards (a bit like the spokey) but the entries were not perfectly sized so it didn't actually fit over 13g spokes without some fettling. The slot design worked (an improvement over a basic square slot for sure) but the fit needed to be much better (than with a corner entry 'diamond slot') on the nipple in order that the key drove well and that particular key also scratched spokes if there was the slightest kind of nipple kink. I may yet cut it in half and make two smaller keys out of it. Probably this will require some welding to extend the parts of the key that are held.
Traditional circular keys
with many square slots tend to round off nipples if the fit is poor (like any key with a square slot will) and also scratch spokes up if there is any nipple kink. I find building with a key like that peculiarly frustrating, in that one tends to lose track of which slot is being used, resulting in much wasted time. However since I cannot buy better key designs in all sizes, I still end up using these from time to time. The Park tool three slot key is a slight improvement in terms of losing track of the slot only, but then it has far fewer slots to start with...
Note also that nipples vary quite a lot, not just in square size. Plenty to be found with slightly rounded corners on the square. Obviously these round off more easily than most and you need a well-fitting key to drive them reliably.
cheers