The Aurora-R7 accepts M.2/NVMe so it can use any NVMe-SSD ... as that is the industry-standard now-days. M.2 is the slot. 2280 is the size (or form-factor). Samsung 970 or 980 SSD will work, EVO or Plus is fine. Traditionally, "Best" is Pro-Series (if they still make those). Additionally, PCIe Gen-3 is backwards compatible with Gen-4, so no problems there either.  
Hello folks please help me , i currently have the R7 with the optane and i am trying to change it to an SSD i was planing to get the evo 970 and i heard it fit my R7 but i really want the Evo 980 since its not a lot difference in $ , but does it fit the R7? thank you so much
Aurora R7, Help me with SSD