The best cryptocurrency i used is the BITCOIN BTC because of the popularity of this coin compared to others. This is the best and trusted cryptocurrency in transfering funds in the blockchain market, tested and proved it for now.
I personally like to use Litecoin. Transactions are quick and cheap, plus it is reasonably known crypto, member of top 5ish. I use Erhereum for sending only for Ico purchases. I prefer LTC all day long, as ETH tends to get congested and expensive. Latest example happened just few days ago, see this article that explains more:
https://bitcoinist.com/is-a-new-exchange-to-blame-for-the-ethereums-network-congestion/