kSro is for legit better since there aint any public bots;
Both have 1x rates > official;
kSro Lvl 105 is cap
cSro Lvl 110 is cap
cSro got a higher foreign community i guess. cSro has got a free bot which is based on keypressing and it works fine for chinese chars along with a pet.
cSro has some nice VIP servers which offer 2x rates at weekend. 90% of the servers are easy or populated, few are crowded.
kSro gives you till 6D SOS weapons; at cSro you get few scrolls and so on, lvl 1+77 Weapon which is almost the same like a NPC 6D weapon and 20k SP for free. With a bit of luck you will get some free ong farming, or even academy and lvl fast to 40. Both have the possibility the buy/sell silk items through stalls and stall network.
A bit mixed those informations, i dont know that much about kSro, but im playin cSro and its kinda nice; on the easy servers you can kill Uniques even on your lvl, on servers which are merged or higher populated you will need to camp or have luck to kill them.
Have fun at whether Silkroad you go for :)
kSro is for legit better since there aint any public bots;