I have tried milin as well and I personally preferred my time with her. Milin is a bit older (my guess) and I enjoyed my conversations / service with her more than I did with Natasha.
Also it depends on what extras you are after. milin when I saw her and looking at past reviews doesn't offer anything beyond NHJ (could have changed though).
Not to take away anything from Natasha which is good in her own way, but my choice is Milin but as always YMMV and everyone's preferences differ.
Regarding shop loyalty I leave that up to you but I usually do like to explore beyond one shop only.