What would be the best iOS to Jailbreak and Unlock my 3GS

[iMore Question]

Hello as the tittle says im looking to upgrade my iPhone from 5.1 to a 6.x.x but I need to be able to unlock.

What jailbreak & unlock you guys recommend ?

Thanks

 

[Orien2k]

I forgot to say my 3GS is new bootrom and modem version: 05.13.04