Samsung Galaxy S6 SM-G920I vs Samsung Galaxy S6 SM-G920F

I am buying some unlocked cellphone for my company, and we mainly use it on the T-mobile network. We fall back to use 3G for most of time. What one from below is a better version?

Samsung Galaxy S6 SM-G920I 
Samsung Galaxy S6 SM-G920F 

https://support.t-mobile.com/thread/92908?start=0

LTE Frequencies:

1700 MHz & 2100 MHz AWS band 4

1900 MHz PCS band 2 (in refarmed areas)

Lower 700 MHz band 12 (in development) / in service in selected areas



3G/4G Frequencies (WCDMA):

1700 MHz & 2100 MHz AWS band 4

1900 MHz PCS band 2 (in refarmed areas)



2G Frequencies (GSM/GPRS/EDGE):

1900 MHz PCS band 2