What are the pros and cons of vinyl gutters?
The weak points in any guttering system are where the various sections join. If the gutters aren't fitted correctly then any system will leak.

So look for a system that has an easy to fit joint, or perhaps one where the joints are bonded.

As long as they have the capacity to carry the volume of water you expect then any correctly installed system will be OK.

One more thing, make sure you maintain them. Check them at least one a year to make sure they're not blocked, more often if you have overhanging trees. Don't lean your ladder on the gutter itself. Lean it just below or get a device to push the ladder away from the wall.