Hi, I have used ImageGlass recently & liked what it offered. Its basic image viewer & is great with gifs which is personal favorite. Irfanview as suggested above is a good choice too. Another alternative I know about is Zoner Photo Studio X which has good editing features. I am not allowed to post links yet so you have to search for yourself Thanks for XnView suggestion which I did not know before. I will try it out.
It should be noted that Image Viewers are very much a matter of personal preference. Thus, there isn’t really best choice for everybody. Furthermore, it’s difficult to know beforehand from the viewer’s spec alone, without actually working with it, whether it will be a happy choice. A good way out, so that one doesn’t have to install and uninstall several viewers, is to go for portable versions, which require no installation and are easily removed. And once the favorite is found, it can then be installed.