Hello as the Subject implicates, I would like to know which is the best online BTC in order to store my BTCs. I know some software wallets like Electrum but I would like to have an online in order to access it from anywhere.
First of all, dont store bitcoins online. Store it in software wallet on your PC (not on mobile phone).
Its safest place you can get aside from hardware wallets. Maybe you can consider also paper wallet.
From online wallet i would recommend blockchain.info / com . I would never do that before because they failed couple times in the past, but in past year i didnt hear anything bad about them.