between those two, i support the cotman.
HOWEVER, please consider the white nights set. i dont have this myself but it's a palette i've had on my list for several months now. it's the same price but the white nights is artist-grade (professional) paint. also, this Schpirr Farben set is also artist-grade. i also don't have this myself but is on my list. you can find reviews on youtube.
PM me if you're interested in my in depth review of the cotman pocket box set. i have this one.
EDIT: i'd like to add some pros and cons. the white nights set is very well known and has been around for a long time. many artists will vouch for it. however, the pans aren't of 'standard' size. as for the schpirr farben, that one is quite new i believe but it has great reviews. also, the metal box it comes with is versatile.
also note that these two sets i mentioned, both don't have the colour white. so you get 'more' colour which is very good in my opinion.