Sanji's observation is advanced though, like in PH when in Nami's body recovering Kinemon's abdomen. He may not have future sight but it is still advanced..
Sanji's Observation is not advanced at all. All he did was sense Kinemon's body which literally any Haki use can do.
If we want to talk advanced...
Momonosuke can sense Luffy and Kaido all the way from floor 1. He can sense 5 Floors up.
Sanji is literally on the same floor level as Momonosuke. He can't tell where Zoro or Law came from. He didn't even know he was fighting Kaido and Big Mom? Yet, Momonosuke can sense everything happening all the way from there. Sanji doesn't even know Luffy's getting weak which Momonosuke knows.
Luffy couldn't tell where Sanji was despite being on floor 3 with Sanji.
Sanji can at least sense 0.5 Floors radius. Luffy's not capable of even that nor is Jimbei. Momonosuke can sense 5 floors up? 10 times what Sanji can and much more what Luffy and Jimbei can.
Momonosuke is more or less Enel.
In terms of ability to hear voices... the ranking is:
- Momonosuke - 5 floor radius.
- Sanji - 0.5 floor radius.
- Luffy and Jimbei - Less than 0.5 floor radius.
Momonosuke is a monster in terms of hearing voices and Sanji's arguably the best at hearing voices within the SH crew.
As for prediction and foresight, Luffy's the best since he can see the future which Sanji can't.
Luffy can also sense emotions, so he's a far more complete observation Haki user than Sanji since he sees the future, senses emotions, but really standard ability to hear voices.
Only people with range greater than Momonosuke that we know of are Rayleigh who could sense the entire Island of Ruskaina and Enel who could hear the voices of everyone in Skypiea.
