Although I like the black border on many of them, I do really like the fresh springy look when a white border and bright colours are used. Just google the words "granny square afghan" and you will see that literally thousands of variations have been done. The blanket has been made by many crocheters across the world of 40+ years.
There are two other styles of aghans that I really like. One, I guess, could be considered a variation of the granny square. It is called the Babette. I love it because of the large and small squares and the way the colours are exchanged from one square to another. If I was going to make an afghan, I think I would start with the Babette. Here's just one example of one still in the process. This is probably about 1/4 of a full blanket.
The second style I like, currently flying off people's hooks right now, is the 'graphghan". This is where an image is charted out and then the whole afghan is crocheted like a large pixelated image. Again, you have to google it to see the incredible pool of talent and variations that have been done - everything from Walter White of Breaking Bad, to Disney princesses, sports team and college logos, to images of pets or family members. Computer programs and/or apps can help you create your own personalized images and some will even chart out the colours you need.
Of course there are many, many other styles of afghans done including Tree of Life, Ripple and the list goes on. Did you have one in your house? Or do you currently have one? What's your favourite TV afghan?