Having experience of both makes I will say that I prefer the Winterhoff.
Unlike the Al-KO which has two levers to operate, the winterhoff has just one which does both jobs, and can be used with a standard towball.
Also, the hitchlock for the Winterhoff is far superior to the Al-KO and easier to fit.
If you are towing with a 4x4 that has the spare wheel mounted on the door, I would recomend the Winterholff as it will not come into contact with the spare unlike the Alko