eth classic's smartcontract's will be the same as ethereum? Or it will be worst/better?
Probably yes.. since they have same core source code...
probably.
As far as I remember Dexaran (Ethereum Commonwealth) wanted to use another language, Viper because it's more secure.
Found a quote of Dexaran himslef: "We all know that smart-contracts are often hacked. It is caused by problems of Solidity programming language. As a smart-contract auditor I can say that Viper could significantly improve readability of smart-contracts and boost their safety."
Interesting, EOS recently was noted at having a found vulnerability itself... here's a link to an article about this potential in regards to EOS...