They're all made to standards.  Some main things to note are for kids, make sure they're the right size, have head/neck support collars and a strap that goes under/between their legs so they can't slip out of them.

If you're new to boating, then consider doing a course:

https://www.coastguard.nz/education/day-skipper-intro/

For adults I like inflatable lifejackets. But that's on a yacht where you're moving around the boat and a standard lifejacket is cumbersome. On a motor boat, then that's not so much of a problem.  The downside is that if you got whacked on the head and fell in, then it's not going to inflate itself if you're unconscious so can't pull the toggle.  You can get self-inflating vests, but you've got to keep them dry, so if you're in heavy seas as some sailors have found, if you then fall overboard and the vest inflates under a tight waterproof jacket, you can't breathe unless you deflate the jacket, choosing between death by being choked or death by drowning doesn't appeal to me.
Because the inflatable jackets aren't uncomfortable to wear, then we wear them all the time, despite that not being a regulation (boat over 6 metres). 

I think the coast guard can check jackets - if the foam has degraded etc.  (They do this for free I think with our local boating club - I think they attach weights and put them in a drum of water, to see if they maintain the buoyancy rating as labelled, check everything else out visually, stitching, clips etc.).

If the ones you got look shabby/worn, then I'd replace them.

Final thought - make sure you (or anybody else) never falls overboard.  If there's a bit of a chop then trying to find a person would be a nightmare.  Then on a nice calm day with the anchor out, try hauling someone who went for a swim back on board, having them act limp/incapacitated.  Then imagine what it would be like trying to get a half-drowned person back on board in a rough sea.

Thanks for your reply. We are new to boating and my husband has joined the Coast Guard and signed up for the course today.

We'll have to go and try some jackets. We will probably choose to wear them all the time, makes sense. Our dogs have good jackets and we are hoping to take them on the boat when we are used to it.