Not all images are suited for the same medium, size or place.
With this I mean that more often than not there will be images you love that, nonetheless, you would never choose to print and hang on a wall on display, but that would be at the same time your first choice for a book or, maybe, for a small print, the kind that goes in a nice frame on a desk.
Size of the printed picture, its subject, if it is color or black and white, place where you want to display it, printing size and possibly even the weather that day or what you had for breakfast all will play a role in the process of selecting which picture will end up in your “Favorites” folder and for which purpose.
Nice for a book, IMO, but not so much for a large print, like most street photography
In the same way some image will work best when printed relatively – or even really – small, so that the viewer will be able to encompass the entire scene with a single look, while others will be maybe even terrible at small sizes, but will gain a new life and meaning when printed at a size where the details will be able to guide the eye in a path inside the frame.
Selecting pictures for a specific purpose – for example to hang on your walls – for this reason might be depressing, because you will, possibly, end up with very few favorites if, generally, your style of shooting tends to result in photos more suited for a book or similar medium. The same applies in reverse, obviously.
It doesn’t look like much here, because you’re seeing it too small;
this image begs to be printed fairly large
As for the subject etc., there is not a clear cut rule, in my opinion. I can just say that, in a really wide general sense, I tend to find street and journalistic pictures less appealing for display on a wall, but again that’s not always the case.
And to top it all, like it wasn’t a confusing enough matter, it will always be your personal taste to have the last word. So don’t get discuraged if your walls are bare: maybe you’re just more of a “book-photographer”, or vice-versa don’t cry if you’ve never been able to stitch a decent sequence of images together for a book, but you don’t have a square centimeter of your walls empty; if that’s the case just go collaborate with a gallery!
Take a look at the pictures of yours you like the most and you will have another tool to better understand what kind of photography speaks to you.