My reasons:

BTC - The King
ETH - Smart Contracts
XSN - Decentralized dApp Eco-System Powered By Masternodes
LINK - Decentralized Oracles
ARK - Scalable Blockchain Building Platform - Point Click Blockchain.

Been here since early 2016, sadly sold the majority of my ETH too early, and sold off a ton of Ripple late 2016, as it wasn't performing very good against BTC.

Biggest sleeper of all of these is XSN, followed by LINK and ARK.

What do you guys hold?