The Istanbul cymbals are all great. I have played agops for years and loved every one. However, the only piece that has earned a permanent spot in my setup are these Mehmet Sultans. Usually the agop signatures are considered to be top of the line, but the sultan hats are fantastic in every way. I have never played any other cymbals from that specific line (the are sort of hard to find), but I have a great impression.
These cymbals are very dark and dry. They look like they would be, due to the prevalent hand hammering and molding techniques. They are also very warm, extremely rewarding to listen to. Even out of musical context, by themselves, the are some of the most pleasantly musical cymbals I have ever heard. The chick sound is nice and punchy, and the bell is amazing. The hand hammering on the bell sounds super dark and clean, though you really have to crack it hard to produce loudness.
Dark, warm, and dry (3 of my favorite words) are usually associated with jazz cymbals. The Mehmet Sultans are versatile enough to play most styles. Of course, 13 inch hats with this type of character aren't the best for metal or hard rock. However, these have served me well in almost every other genre. They have a unique appearance, and partly due to their relative rarity I accumulate many compliments. They look old and vintage after a few years of playing and capture a bit of the "old Zildjian" sound that is so sought after these days. The only disadvantage of these is the size, as I would prefer a 14 inch hat to increase the versatility a little bit. This isn't a big deal though, as I am deeply in love with these hi hats. I will give them a 10 out of 10.