The key thing in my opinion is to ensure that the bike fits. A 'good' bike can easily become a torture device of it is the wrong size or not adjusted properly.
Related to this, I would recommend investing some coin in excellent bibshorts and a saddle that's right for you. These things will make the biggest difference to your ride experience.
A good bike shop will be able to address the above issues for you. I wouldn't recommend buying your first roadbike online. Too much uncertainty.
Subject to this. The 'frame over components' theme above is a good one.