These are nothing like the RR 757 engines. These RE BR700s (F130 mil designation) are the same motors as those found on G5s and globals (and 717s), among other applications. They seem to work pretty well in those applications from what I understand, and 1) are already in the USAF inventory and 2) have a ton of proven historical data.
The GE options were the CF34-10 or the newer passports. The former is meh/older tech. The latter (passports) should be pretty solid (powering the new large globals), but don’t have a lot of history as they are fairly new. I think the passports are made with the same or similar cores (or at least tech) to the CFM LEAPs on the MAX/NEO. Should be a good motor, but not a lot of data on them.
The pratt option was the motor that powers the gulfstream g500/g600, the PW800 series, which is the same core as the geared turbofan Pratts on the A220. Gulfstream made a big move switching from RR to pratt for the G500/600. They look like solid motors. But, like the passports, are relatively new.
The new tech motors often have hotter temps and tighter tolerances, and that can mean a bit more finicky maintenance. As a datapoint, the on wing time of the CFM LEAPs on the NEOs has been underperforming targets and they have needed to get overhauled earlier. That was one of the big reasons frontier switched from CFM LEAP to pratt GTFs for their future NEO orders. And the pratt GTFs had tons of issues when they were launched as well. Trusting either of those cores to be integrated with the buff could be asking for trouble.
The latest and greatest/most efficient motor isn’t always the goal of military (or cargo) planes. I think the USAF probably made a good (conservative at least) choice picking a tried and true, reliable and fairly easy to maintain, already-in-the-inventory, not entirely dated technology engine. The marginally better/newer bizjet motors that don’t have much historical in service data (and none in the military) probably didn’t offer enough of an advantage to be worth it.
I think it was a decent choice.
just my $0.02