keks
4948
very very difficult call
I think both have their merits and it really comes down to what you think complements your collection and wearing needs the most.
The full bracelet aluminum I have tried in the simpler Octa Sport and thought it felt superb on the wrist. I believe the case is very similar on the centigraphe at 42mm so imagine feeling is similar. it is a beautiful color metal this aluminum. I am not sure where I heard this and perhaps it has been remedied, but recall someone mentioning years ago that there are cases where this version suffers from discoloration in the metal when exposed to sweat or saltwater. No idea if this is a fact or hearsay and also do not know how this metal oxidizes but perhaps something to consider knowing more about before committing.
The full bracelet titanium I have tried in 42 and 44mm. The 42 is more far more balanced in my opinion but I do like the absence of rubber details on bracelet and case on the 44mm version. But since you mentioned the 44mm is not even a consideration will not discuss that any more here. The dark tone of the titanium on this is extremely elegant.
So, if I had to choose one... if I could confirm that the aluminum is safe from discoloration (yellow stains from what I heard) and has an acceptable hardness level this is the version I would pick. Simply because I think the tone of the metal is gorgeous and the fact it is made of aluminum is pretty darn cool... sorry for the ramble but hope you find something in here somewhat useful! Good luck!