I didn't use any kind of wallets, just i invested bitcoins only. Some body told me, mobile wallets are better than the desktop wallets for the new bitcoin users.
Yes you are right sometimes it is better to invest it in other way or in an investment site or trade it. And if you want you may save a little in an online wallet is safe there if we are putting a security on it and if the site is legit and it is serving many people for many years i think you can put a trust on it .