Bitcoin Forum

As suggested on topic

For sizeable amounts and/or long term, none.

Litevault for wallet, GDAX, polo, BTC-e for exchanges.

GDAX are run by the guys in coinbase, but polo and BTC-e seem to be abit opaque, no credentials of the team, though some might actually want it that way.

run litecoin core if you can and want it, because full nodes is always best thing you can hope for, in sense of privacy, security, helping the network and many other things.
if not run Electrum-ltc which is the SPV version of litecoin wallet which means it doesn't take much space and is reliable enough, you can make a cold storage with it also.

for exchange you can use many that offer it, poloniex, bittrex, btc-e, are the top in my opinion.

if you write about online wallet exchanger is nothing save is big litecoin
is good use dekstop wallet
if you say about exchanger trusted, majority excanger support litecoin and trusted too

1 poloniex
2 bitrex
3 kraken

and more

For online wallet I would recommend LiteVault.net which handles coins all in your browser, and cannot be controlled by the site owners. It's secure.

For exchange, I would recommend GDAX, which is the Coinbase exchange. Coinbase being the biggest legitimate cryptocurrency company. GDAX was also built by Charlie Lee (coblee), who is the director of engineering at Coinbase, and he is the person who created Litecoin.