Hello,
the Ram type rather will not have a huge influence on the calculation speed. The most important one is a processor.
Overall look for a processor with a lesser amount of cores and high frequency on a single core( there is no reason to put more than 8 cores, the software will not get a huge boost for that).
So from these two i7 will be a better option. Especially the i9 has E-Cores which are created for the background processes which work on very low frequency and for the processors the Solver application is the background process.
So after buying i9 the first thing you need to do is disable the E cores in the BIOS. So you cannot use the feature for which you pay.
BR
Karol