You select the end from which the more substituted carbon comes first. So which end is it?
Also, you don't need to do the sum for aliphatic compounds, that's only for cyclic compounds.
Strange rules. Would not be better if I took into consideration all substituents? In other words shouldn't I pay attention to the sum of all substituents?
Well, strange rules!
I don't spend much time on IUPAC (I've mentioned before on this forum that I think a lot of the conventions are illogical and unhelpful). That said, if I have to name a compound, I usually cheat by going to some chemical database that names the compounds automatically (PubChem, SciFinder, and Sigma are all pretty good). In this case, I used the PubChem structure search, which returned this little nugget: https://pubchem.ncbi.nlm.nih.gov/compound/23333527