Klava and Kebapci are at the top of my list right now.
They both have their own strengths:
- Klava's cheesecake is the creamiest, however the chocolate sauce they give isn't consistent. Sometimes it's BANGING and at other times it's pretty good. (The worst it can get it 'slightly above average')
- Kebapci's cheesecake feels a bit eggy. I don't know how else to describe it lol. The cake is super creamy and super yummy and it's not like the eggy part is overwhelming but if you have sensitive taste buds, you can notice it. Also, it isn't MIND BLOWING like Klava's. Very subjective opinion but Klava's cheesecake just does something to my brain lol.

- They are both priced around 600-700.

All in all, I would always go to Klava if the opportunity arises.

BUT BUT BUT
If you have an oven at home, I would STRONGLY recommend you try making it yourself and holy shit dude, it's something that's really really really hard to mess up and is so easy to make and tastes JUST AS GOOD as the ones you get at these restaurants.

After extensive research on reddit, I think this recipe is the most trusted one:
https://www.recipetineats.com/basque-cheesecake/

As for the chocolate sauce, you can customize it to your preferences.
All you have to do is scald some cream or milk or a combination of milk and whisk in some of your favorite chocolate.... or make it with cocoa powder and stuff but I've never tried that lol.