We have both, thats mainly because PLB didnt have sophistication when we purchased EPIRP. I would go for PLB and if you can afford it get two. One for vest and one for the ditch bag.
We have two of the 2881
ACR 2881 ResQLink+ PLB Personal Locator Beacon
We have 1 2842
ACR Global Fix Pro 2842 Cat I EPIRB