It depends on the number of coins you are holding. If its a low amount you can keep it even in blockchain.info or any other web wallet. If its low to medium amount you can keep it in Core, Multibit, Electrum. For peace of mind do like I just did 2 days ago and bought the Ledger HW.1 wallet, a malware proof hardware wallet for a really cheap price of only 15 Euro or 0.027 BTC. You can sleep well at night knowing that even if your computer security is compromised your bitcoins are safe with this wallet as every transaction is done through the secure malware proof chip of this wallet. I can't wait to have it, should be here after a few days.