Right now, I'm using the Kodansha Kanji Learner's Dictionary, and have been quite pleased with it. However, one of our Japanese teachers recommended the Nelson Kanji Dictionary. A quick Google search tells me that it has 70,000 kanji (compared with 2,230 in the Kodansha one). It seems a tad overkill for our level, but she recommended it knowing that most of us already have the Kodansha one.
We shall be doing a module in Classical Japanese in January, which is where this one might come in handy. The unusual kanji would inevitable be explained to us, but I am the curious type. Ordinarily, I'd buy this other dictionary without a second thought, but it's quite expensive, especially for a student like me.
So, what are people's opinions on it? Especially compared with the aforementioned Kodansha Learner's Dictionary.
I cannot recommend Nelsons highly enough. You will never regret buying this book. I say "book" because it is so much more than a dictionary. I have had thousands of happy hours with this, from the time I was a fairly low-level student of Japanese. If you have any real interest in the language and in kanji you will get so much out of this. If you want more details of how (and why) I am happy to provide them.