I have a WRT1900AC, what would be a good upgrade?

WRT1900AC v1 Firmware: factory to dd-wrt, initial installation image factory-to-ddwrt.img 2016-01-05 30,63 MB
WRT1900AC v1 Firmware: webflash image ddwrt-linksys-wrt1900ac-webflash.bin 2016-01-05 30,63 MB

which one should I use?