What Galaxy S5 version should i buy?

Hi people! I have these versions of the Galaxy S5 available to buy at the same price, all sim-unlocked:

SM-G900A
SM-G900F
SM-G900M

I live in Argentina, and the LTE bands available here are 4 (AWS, 1700) and 28 (APT700, 700 MHz), so both SM-G900A and SM-G900M should connect to 4G.

But i read that the SM-900A has a locked bootloader so i cant upgrade it to Cyanogenmod or other non-official roms, which i will do for sure. In the other hand, the SM-G900F is not compatible with argentinian LTE bands but i read that i can unlock the bands rooting the phone and using QPST.

I will use non-official roms and stock-based modified roms, so, what version should you recommend? i read that SM-G900F is compatible with mostly non-official roms, while SM-G900M is only compatible with certain roms. So, i should buy the SM-G900F and unlock the LTE bands or buy the SM-G900M for the unlocked bands and resign using some roms?

Edit: i have disponible at the same price, the Sm-G901F lte-a version, but there isn't too much info about this version.

Help please! Thanks in advance.