Just coming back from 10 days in Istanbul, 5 days in Hagia Sofia Mansions and 5 days in Hilton Bomonti.
Hagia Sofia Mansions:
Okay location 10-minute walk to the Marmaray Sirkeci station but next to Topkapi and Hagia Sofia. Area is a bit too touristy, you get shouted at every 2m if you want to go into a restaurant.
As Gold, got upgraded to Topkapi Suite which was really nice.
However the houses are not very well noise-insulated, you can hear every car/tram driving past. The breakfast was also rather basic and they charged extra for things like pancakes.
Hilton Bomonti
Rather far from the metro, 15 minutes walking and it's not an even footpath so difficult with luggage. No suite upgrade as Diamond. The lounge is still closed, offerings at afternoon tea and dinner (there is only one option) are rather poor, we skipped it after the first day. Breakfast has a good selection.

Both hotels seemed quite busy, but I didn't like any of them particularly. Neither hotel is very well connected to public transport, and taxis are not great (one ripped us off and the other took off his mask and started smoking - and that's booked through Uber!). As a tourist, if you are not chasing status, I'd say forget about Hilton in Istanbul and go for a nicer independent hotel near Taksim/Sishane - food in Istanbul is really cheap anyway so no point in using the lounge or breakfast.