PIVX is better in my opinion. 

Key differences between PIVX and DASH:

100% Proof of Stake – PIVX supports an advanced version of Proof of Stake (POS). This is a system that relies on master-nodes to verify transactions instead of miners. PIVX is 100% Proof of Stake whilst DASH is only 50%. This means DASH still relies on miners whilst PIVX does not.

Seesaw reward mechanism – PIVX uses an advanced mechanism to distribute block rewards. 90% of the reward is distributed to the masternodes and stake nodes, whilst 10% is distributed to community projects.

Availability – PIVX is a newer currency than DASH and less availability. It is traded on less trading platforms. 

PIVX solves a lot of problems that DASH has and it is much cheaper. It will be interesting to see how it plays out.

PIVX. FASTER, MORE COMMUNITY ORIENTED, CHEAPER, COOLER

I have to disagree with both of the current comments here with regards to PIVX. Although both coins are good, however "there can only be one" major crypto to succeed say Bitcoin, let me explain why:

So DASH is aiming at a bigger audience then PIVX and have a strong committed not to mention dedicated team working on it.  They will be releasing Evolution later in the year which will assist with the above and ensure that even your grandmother could use cryptocurrency, how cool is that? This is something that PIVX will not have since its looking in the opposite direction. Any new releases with DASH will be released on the DASH platform, any platforms such as PIVX will have to wait to see and try to incorporate these into their own.  DASH Marketing is far superior then any other coin out there,  not to mention it also has already made its mark within crypto for several years.  PIVX is fairly new and has still not made much noise - at present i feel it's being pumped by big whales and the price correction is just around the corner, so you will see a huge downfall when whales sell.

 PIVX is a great short-term investment however in the  long run, Dash would likely outshine PIVX in terms of user adoption and thus, market cap.

Early adopters would be drawn to the stability of the large user base and convenience as a payment medium, to merchants. The trade-off in privacy and governance would be instant, as they opt for something more understandable and relatable.