MIFARE DESFire EV2 has a longer read range than MIFARE DESFire EV1, but unless your system provider has updated their software to support EV2, that is the only new feature you will be able to enjoy today.
Since EV1 and EV2 use the same very secure AES-128 encryption, it is safe and reasonable to purchase EV1 cards now, configured to work with your existing system and readers. If, or when, applications that support the new security and multi-application features of EV2 are made available for your institution, the upgrade to EV2 cards can be made at that time. The way things are going, it could be a while.
NXP manufactures the family of MIFARE 13.56 MHz contactless smart card Integrated Circuit (IC) chips that are widely used around the world for transit and other types of payments, general identification and physical access. MIFARE Classic was introduced in the mid-1990s and continues to sell in very large quantities, but it was not designed with robust security features which could withstand the increase in computing power that the last 20 years have seen. MIFARE Classic has been very useful and inexpensive, but it was notoriously hacked in 2007. As a more secure successor, the MIFARE DESFire chip was introduced in 2003, but it too was soon considered vulnerable to attack. In response, NXP introduced the much more secure MIFARE Plus, but it didn’t really catch on in North America. The MIFARE DESFire EV1 chip has been NXP’s first widely distributed, really secure chip, incorporating AES data encryption on the card and during communication with a reader. MIFARE Plus EV2 was introduced recently, incorporating a similar security level to DESFire EV1.