Consider other features of packages too
I have also been seen these 2 packages but you really have to consider other things apart from the rates.
Btw, banks cannot adjust SOR or SIBOR.
Firstly, the SOR is not the board rate, SOR is also tansparent to the public like the SIBOR and as such, SIBOR and SOR move in tandem to each other, sometimes SOR is higher than SIBOR and sometimes SIBOR is higher than SOR, but they are really not much different as you already stated that the SIBOR is 0.686% and SOR is 0.7%. The difference though, is the "spread", like the 0.65%, 0.85% and 1.35%, etc. and other features in these loan packages like the lock-in periods and redemption penalty apart from the rates.