Patagonia vest is very good but Pricy. Also beware that the 'Impact' vests are often designed for flotation with SOME impact resistance.
I have been wearing impact vests for 10 years. O'Neal Gooru for 7 years, Patagonia for 3 years. Almost every session (90% of the time e.g. when > 5 feet in California). I once cracked my ribs through my O'Neal Gooru vest which didn't help the impact but it helped me FLOAT when I couldn't swim.
1) Wear the vest under your wetsuit, or wetsuit shirt. They will all ride up
2) In warm water be sure to tie it to your shorts. They will all ride up and choke you.
3) Consider this for impact. I found a cheaper alternative on Amazon that MAY be better for impact but not so much for float.
Equestrian Impact Vest - This is TRULY for Impact. Alternately I wore a high school football rib protector under my Gooru Vest for 6+ years.