GOM is a good player.. it was developed in Korea. They use it to stream Starcraft matches and other stuff over there. There is another player I like better, personally, which is called KMPlayer. It is also developed in Korea and competes with GOM player.
I'm not sure why you would have blocky or pixelated images with VLC player. I love it personally and use it all the time. If you use Firefox, there is an add-on called, "VLC Youtube Shortcut," which lets you right click on Youtube videos and select either play or "enqueue" to VLC player. This lets you instantly watch any Youtube video via VLC player. You can also right click on a Youtube playlist and send it to VLC player. You can then save the playlist onto your computer and open it at a later time.
These are my main players, and I don't really have a need for anything else. However, I have found that KMPlayer does tend to inundate you with features and settings. It gets kind of daunting, actually, if you are just a casual user. I had to turn off the feature that forces KMPlayer to stick to the original video's resolution. I like being able to drag the corners and resize the video. I also like it to upscale the video when I put it into full screen mode instead of it playing at the original resolution, assuming the resolution is lower than 1080p. These are settings which VLC player has enabled already, but not so with KMPlayer.
Whichever one you choose, they are all amazing players.