Personally I like Taber's but only because I have been reading it for about as long as I could read. I think I started with the 11th Ed. Up to something like the 17th or 19th now. I think this one gives a bit more information rather than a strict definition, which can help with retention.
The other big ones would be Dorland's and Stedman's. I really don't think you could go wrong with any of the three. But if you want it to be useful you have to use it. Read it on a regular basis. Look up everything you don't understand. Re-read it from time to time. Add your own notes in the margins. These books can be incredibly useful.
Stedman's Concise comes with a CD ROM which allows you to type the words into your computer. This is much quicker than doing it by hand. No matter which dictionary you buy this is a must have feature.
Stedman's electronic is great. Not only can you access it quickly on the computer and do searches, but ours had an add-in dictionary for Word so when you are typing in sternocleidomastoid in an outline or something, you don't get Word telling you that it is misspelled.
I have both Taber's and Stedman's concise dictionary. Taber's is far superior than this version of Stedman's, but I can't speak for Stedman's complete dictionary.