One of easiest way to create and access Ethereum and erc20 token is MEW web interface. My question is , is it safe to keep big amount in MEW or better not to rely on it.
Its safe and so far all of my coins we're intact nor lost in my wallet since i've start on this market.Just be sure that you wont really commit mistakes.
-Stay aware with phishing sites because there are tons of them.
specially if using google search.
-Dont share up your keys or phrases no matter what.
-Dont click out links to avoid malwares.
I do also agree with others recommendation but talking solely on MEW then i can say that it is safe.
Its up to someone on how to they do keep their keys safe.
I might have to disagree with you somehow on keeping your crypto on a web wallet especially if it's a big amount of money, although just like what you have said it all depends on someone on how they would manage to keep safe their private keys. Or use something like a Ledger to keep their big amount of ETH and write a back up keys for their wallet. It's safer to keep it your own crypto off the internet to avoid of being stolen or getting hack.
So basically keeping your money on a MEW web wallet is totally safe as long as know your passphrase but it also depends on a person of how well they were going to protect their own money/crypto in a web wallet.