PLEASE NEVER USE ANY SORT OF ONLINE WALLET, BLOCKCHAIN OR ANYTHING. [1] Electrum and MultiBit do not transfer your private keys anywhere and are comparatively much safer.
Most wallets that are safe do not offer a way to sell. Some online wallets like Xapo offers the feature of withdrawing through their debit cards. It won't be safe nor cheap.
[1]
https://www.reddit.com/r/Bitcoin/comments/573lis/it_looks_like_blockchaininfo_has_been_dns_hijacked/- Hackers can very very easily compromise your security through man in the middle attack.
There were several issues affecting the RNG in the past.
I guess ill give Electrum and MultiBit a look. Can you give me a safe place to buy Bitcoins.
Also, FortueJack offers a way to buy Bitcoins through their website. would that be safe?
I would recommend Bitfinex or coinbase for buying Bitcoins. When using coinbase, it is recommended to use a mixer before transferring to your own address.
-snip-
Since you appear to be new to Bitcoin, I would recommend you not to use offline wallets.
You should use don't online Bitcoin services like Coinbase and Xapo.
Big Coinbase and Xapo can let you store ,send, receive, buy and sell Bitcoins. Both of them are trusted ones.
Benefit of Xapo would be that you don't have to pay transactions fees(not very high).
For you, i would recommend ty use Coinbase or Xapo for selling Bitcoins rather than using other exchanges.
Hope it helps
There is 0 disadvantages of using a desktop wallet especially since nearly all of them uses a seed which would allow the addresses to be accessible from several devices. The UI is friendly enough, even for paper wallets and Armory in offline mode.