It is generally accepted that "simplest form" is the goal.
is almost universally accepted as simplest in the form
is a bit trickier, but still requires extraction of all perfect squares before anythone thins it is "simplest".
For me, this is done, but there remains another convention that says redicals in the denominator are evil. I don't tend to agree with this convention, but if it is in your curriculum as "simplification", your teacher will be justified in marking it wrong if you don't do it. It takes the idea, a very useful idea, of rationalizing the denominator.
It is a purely cosmetic effort. Check carefully to see if you are required to do it. It is also a carry-over from the days before calculators. The last expression may nto be simpler than others at all from the point of view of your calculator. It also takes longer to do this. If you have panic exam time pressure, just don't do it.