It's pretty hard to choose five as it depends on what purpose I've come on the computer for, so it changes quite often depending on what I'm doing - and I use my computer for waaaay too much for so many different things. I can name three at least though them being: MyDramaList, Facebook and tumblr.
Hotmail, MyAnimeList, Amazon, eBay, MangaFox and YouTube are first a lot too, and are depending on what I'm doing, but they are in a sort of secondary category compared to the three I mentioned. Dramas I watch on my tablet with an app, so I don't need to go to a website as I have my tablet with me nearly 24/7!