Ahmet's place is great if you want to be close to sights and the metro.
Nice big room and functional kitchen. Rami and Ahmet were both very helpful and friendly, and Rami went above an beyond to be helpful and communicative.
Only downside is the building (like the others around Taksim) is very not soundproof. Sound travels easily between the halls and rooms.
Other than that, can't recommend it enough.