I would say DASH and this is why:

- Very active, ongoing development with big update on the horizon next year (DASH Evolution https://www.youtube.com/watch?v=N7T-a2xm5c0)
- good choice of GUI wallets
- DASH has a high full node count (4256 right now) because the owners of a DASH masternode earn about 10% interest on the DASH they own
- Cryptocurrencies with anonymizing features are generally very popular and will continue to be popular
- DASH has been in the Top 10 on http://coinmarketcap.com/currencies/views/all/ for a long time now
- development and community are funded by votes from masternode owners (dashcentral.org)
- Currently DASH is relatively cheap with a lot of upside potential: see the chart: http://coinmarketcap.com/currencies/dash/


So especially if you are looking to make a long term investment, you can even earn a very good interest rate with DASH.


dash.org