AniDB

I'm not so happy about the raccomendations that could be founded on Anime Planet.
I think it's not a useful service because the anime reccomended are not similar nor related with the one that are linked to. I suppose that they make raccomendations randomly.

The quality of the recommendations vary quite a bit yeah but it's actually pretty decent most of the time. It's a neat service that's free (except for the space on the page!!!), if you want better recommendations maybe you should add your own ones?

well,

the recommendations are certainly not random, the problem is simply that they don't have a very large base of votes to base the recommendation on.
this makes the "quality" of the recommendation vary quite a bit depending on how many ppl made recommendation for that anime so far.
I am pretty sure that they will improve a lot once more ppl voted.

BYe!
EXP

If you have voted/seen enough anime (over 30 series/movies), then AniDB hint would be more accurate. Try the new/strict system to get a bit closer hints as well.

Since Planet is more used for newbies who haven`t seen that much, these recommendations are useful, but for the die-hard otaku AniDB hint would be much more useful, since it gives a list of recommendations based on your preferences (based on what you have voted/in mylist - compared to what other people with these animes have voted).