Mine changes based on what I've watched/read recently. But If I had to think about which made the biggest impact on me, or which one's I recommend to others it would go a little something like this.
Top 3 Manga (Not series which have spawned Anime):
3: GE-Good Ending: Again, Never thought I would like this one, as I'm not a real fan of romance stories, but I thoroughly enjoyed it. The characters are likeable and more importantly relatable, the artwork is good and it was strangely addictive. Just goes to show, It might not be your favourite genre, but it could still find the manga very enjoyable.
2: Gantz: Would of preferred it without so much ecchi material as I always feel this cheapens a story and the characters. But plot wise I loved the concept and you never know quite who would survive. Also the action sequences, particularly the Nurarihyon alien battle, they were the highlights. I remember feeling exhausted from reading that fight! Also I know that Gantz has an Anime series as well as two films, but the Manga far outshines both in my opinion.
1: Cage of Eden: Excluding the Ending, I loved this Manga and the story. I can't quite place my finger on what it was that I found so appealing about this one, it just really grabbed me. I had so many favourite characters and there was always a real sense of tension and danger to the group throughout the story. Again, the only thing I would say is I would of preferred the ecchi stuff to be toned down. After all, its hard to really feel that a girl's life is in danger when the image provided is pretty much an excuse for a panty shot.
Top 5 Anime (This one's sooooo hard!!!!)
5: Sword Art Online: I enjoyed this one and really cared about the fates of the main characters.
4: Mirai Nikki: Suprised at how good this was. I wasn't initially keen after the first episode, but It pulled me in and I was really glad I stuck around.
3: The Melancholy of Haruhi Suzumiya: Just great, awesome to throw on after a long day at work and chill out too.
2: Code Geass: So smartly written, Lelouch is definitely my favourite protagonist (albeit a Byronic hero at that!) of any series. Just really grabbed me from start to finish and It has so many twists and turns that
I pretty much go back and rewatch it every 6 months or so. If you haven't seen it, then I highly recommend it
1: Bleach: Just because it was my first true steps into the world of Anime and it had an actual effect on my life and my hobbies. It will always have a special place in my anime lists