Arguably the most important aspect of web development, other than getting the website working in the first place is whether to place more emphasis on aesthetics or functionality. Personally, I think aesthetics come with functionality, so a simplistic or functional site is aesthetic in a way. Of course, many people discuss the Golden Ratio when it comes aesthetics, but I find that a simple functional website ends up being more pleasant than a convoluted website. Of course, there are exceptions, but a good balance of both is the best for web development.
There are many decisions that sacrifice one for the other, for example, links are far more obvious when they are blue and underlined and that is understood by a vast majority of users. However, this does not necessarily work for many websites layouts, so a choice needs to be made in reducing the lack of functionality by making links less obvious, but increasing the stylisation. However, most users will still find the links when place in obvious spots or are easily differentiated, this site for example uses an obvious navigation bar and highlights words when you hover over them. This is one of the quickest ways to increase aesthetics without sacrificing functionality.
There are many examples that we could discuss when it comes to web development and aesthetics and functionality, like the location of the navigation bar, whether you have automatic shifting slides or slides with buttons, there is no 100% correct answer for all situations. A great web designer or web developer should be able to find the perfect balance depending on the client.