Well a conviction is a firmly held belief, so what I have learned post jws is that besides the basics of physics, I have no firmly held beliefs. Why? Because everything changes whether we like it or not.
For a start look at jws. What was a firmly held belief in 1870 wouldn't be recognised today. Actually what was a firmly held belief in 1990 wouldn't be recognised today.
I attempt to gather as much evidence as possible before deciding if something is "believable". That includes experiencing as well as reading etc.
Am I happier with my new convictions post jw? OMG... I finally threw off their bullshit (new personality) and became the person I was born to be.