vesselfinder.com I have found tends to lag behind the other sites.
https://www.marinetraffic.com I prefer as initial contact/port scanning but more times than not the owner name and some other details will be behind the paywall upgrade. There is also a tendency on the site to not keep port call history very long. https://www.myshiptracking.com/ is the one I use when doing screencaps on port calls as the history record there is usually detailed and covers a longer period. This site is also very good when ships are inport or very near land as zooming in much better detail of land features like road names comes up. One drawback is the site is partial to searching by the vessel's IMO number.
When I'm interested in a ships owner/operator I've found http://www.vesseltracking.net/ to be very helpful. Again here IMO or MMSI number would be the preferred way to pull up info on a vessel.
Another useful maritime site is https://www.fleetmon.com/ that can be much more useful than vesselfinder.com but be advised the images of the vessels there would have come from marinetraffic.com more often than not.