Top 5 Anime IMO
1. Steins;Gate._ Amazing plot, easily beats Death Note in it. This anime is the epitome of genius. You actually care about the characters. This anime though, requires you to have a brain (not being mean here, this anime is 99% science 1% fantasy). Again, one of the best, maybe the best, anime you will ever see. The plot of the story tackles the possibilities of time traveling, and other theories and interpretations (Schrodinger's cat theory, many-worlds interpretation, and others).
I highly recommend this anime. Must watch.
2. Gintama._ The plot in which there is no plot. The main character is one of the most bad ass and funny characters I have seen. The fights are amazingly good, the comedy is second to none. If you want to laugh yourself to death, Gintama is something you should not miss. The plot is about a samurai that works as a jack of all trades, embarking into different adventures. This anime also mocks other animes such as DBZ, Naruto, Death Note, etc.
3. Code Geass._ Impressive plot. It is based on strategical thinking and wars between humanity and the mind. The character development is great. This anime teaches that the concept of good and evil depends in the observer. The plot floats around an era of total domination, the hero gains a "superpower" that allows him to command anyone. Pretty interesting, a must watch.
4. One Piece._ I don't have to explain, by now everyone should know about this anime. Nice comedy, amazing characters, good plot.
5. Fairy Tail._ Amazing characters, nice plot. The fights are amazing. It has a similar comedic style as One Piece. The story builds up in an era of magic, a group of wizards from the guild "Fairy Tail" embark into different adventures, which are pretty epic in my opinion. It has a nice mood. A recommend watching it.