top 7 cryptocurrencies in 2017

BITCOIN

advantages :-

disadvantages :-

there is a possibility of a 51 percent attack, where one individual or group controls more than half of the processing power on the network, allowing them to consistently win the right to verify payments and thus rewrite the ledger to suit their own ends.
it requires immense power consumption
extremely volatile

BLACKCOIN

advantages :-

relies on a proof-of-stake system in order to verify transactions
vibrant community : maintains an active presence on Twitter, Facebook, Reddit and IRC
offers a client called BlackHalo, which functions as a decentralized currency exchange, allowing conversion between practically any two currencies, as well as other features.

disadvantages :-

low value
doesn't offer enough unique features and utility to make it a viable competitor in the saturated cryptocurrency market
Proof of stake is also a less secure alternative to proof of work, despite the energy savings.

DASH

advantages:-

Dash's key innovation is its Darksend system: In order to make its transactions untraceable, specially designated computers called Masternodes collect and execute several transactions at once, making it unclear whose coins are going to who, like a massive electronic game of three-card monte.
To increase anonymity, users can opt for multiple rounds of mixing to further obfuscate the source of their coins.
This system also means that there is no publicly available ledger as there is with other coins, making it difficult for third parties to analyse your transactions and calculate your holdings.
A key feature of Dash is its X11 hashing algorithm which is a unique alternative from scrypt or SHA 256 because its design allows users with less powerful hardware to still compete to verify transaction, and thus mine coins.

disadvantages :-

It is still possible for an attacker with government-scale resources to break through.

DOGECOIN

advantages :-

Dogecoin is a proof-of-work currency.
Users of a Scrypt-based cryptocurrency like dogecoin can compete to verify transactions on multiple different currency networks at once without having to expend more processing power.

disadvantages :-

Dogecoin uses an algorithm called Scrypt, which is designed to require more computing power to run than the traditional SHA-256 algorithm.
A concern with Dogecoin is its extremely low per-coin value, which stems in part from the extremely high coin supply.

LITECOIN

advantages :-

One of Litecoin's main innovations is the increased rate at which information is added to its ledger
Litecoin transactions can be processed more quickly with a new block of transactions verified and posted roughly every two minutes.

disadvantages

NAMECOIN

advantages :-

Uses the peer-to-peer verification technology that makes cryptocurrency possible to create a decentralized DNS
Namecoin solves the problem that the centralized servers are usually owned by large corporations and governments by taking the responsibility for storing domain names away from central servers and storing that information in a peer-to-peer network

disadvantages :-

Not designed to be a full-fledged currency

RIPPLE

advantages :-
Ripple uses a unique consensus system in which, whatever the majority of computers on the network see happen is what gets recorded in the ledger
It requires relatively little energy to run and processes transactions more quickly than a proof-of-work system
Ripple supports token representations of almost every currency, including fiat currencies, like dollars and Yen, and cryptocurrencies, like Bitcoins, and specialised currencies like air miles and reward points.
disadvantages :-
The system is not perfectly reliable as it can be compromised by network lag or malicious users,