soft armor cuts your mobility and won't stop a lot of shrapnel
You really need to define the purpose for the armor to get the best recommendation. If I were rolling down IED alley in a vehicle, I would want the whole getup, IBA, plates for front, back, sides, neck protector, groin protector, deltoid attachments, etc. Sure, it weighs a miserable amount and little mobility, but in a vehicle it matters not unless you have to make a fast exit (such as being tossed into a canal...).