I guess there is no such thing as the best style. Every style has its advantages. Probably you should consider something that fits better your physical conditions and age.
I'd like to mention sambo in addition to all styles mentioned in other comments. It is based on Judo and very practical since it was developed specifically for military and law enforcement. Combat sambo includes punching and kicking in addition to grappling techniques. As far as I know aikido requires a long learning curve before it can be used practically on physically fit opponents.