I Suggest Judo, cause Judoka are much more then Samboka and the level of competition is higher in Judo, cause It's also an Olympic Sport.
You could train with higher level athletes and improve yourself.
In Italy this is the situation
Judo = a lot of atlets and clubs, Higher level competitions.
Sambo= only a few club , no real competitions (tournament are only a few)
Even in Russia Judo is more practiced then Sambo and almost all Samboka cross train in Judo.
I'm not saying Judo is better, but be a champion in judo is much more difficult then in Sambo ( Look at Fedor, only 3rd in Judo National and then after he start to practice Combat Sambo he won the World Championship in that style.)