I've tried
Xiandai Hanyu Guifan Cidian because it's in (or was in at some point) the pro bundle. I've found it really valuable in 3 ways:
- It's very useful for words that map to English words with many meanings. For example, 应该 is in ABC and CEDICT as "should; ought to; must". You might reasonably expect that it means "must" in the sense of the English modal verb, much like "should". It's something of a clue that other C-E dictionaries leave out "must" (PLC, OCC), but GF really makes it clear in definition 2: 动 估计情况必然如此. So it means "must" in the sense of "this must be a great answer to your question!"
- It frequently has notes marked "注意" that explain how a word differs from a similar word, or cautions against common usage mistakes. For example, 幸亏 has a note comparing it to 好在, clarifying that 幸亏 means luckily in the sense of lucky (luckily someone saved me from drowning), while 好在 means luckily in the sense of a fortuitous pre-existing condition (luckily the water was shallow).
- When there are multiple words that mean the same thing. For example, for 蟾蜍 and 癞蛤蟆 (both meaning toad), GF comes to the rescue when it defines 癞蛤蟆 as 蟾蜍的俗称. Or in complex cases where a C-E dictionary just lists a lot of the same things, GF is more specific, such as the definition for 即 (jí) the GF entry is almost as good as a grammar book about clarifying when it is the same as 就/便/就是 etc.
(Side note: If you are a beginner and find GF intimidating, you should consider the Tuttle Learner's dictionary, because it can offer similar insights, e.g. clarifying that 然而 is just 但是 but only used in written Chinese, as opposed to ABC, PLC, CC, etc all just saying "but")
(Only now I'm reading the GF entry for 但是 and it has an interesting 注意 that taught me somthing. Nice!)