While my exact recommendations would vary a bit depending on the person’s level, the amount of dictionaries they are looking to buy and how they want to use it, my general advice would be :
If you are just buying one dictionary :
Read up on the entries for whichever one has your fancy (But 明鏡国語辞典 is a great starter one, and the one I would most thoroughly advice)
Two dictionaries :
The first one again should be the one that has your fancy, but the second one depends on which of the camps your first one falls in, if your first one was from camp A I would suggest picking one up from camp B for best coverage / biggest variation in explanations and vice versa (Note : I have arranged them in each camp in the order I would personally recommend them for a general reader at this point in time, though this order can change depending on personal needs) :
Camp A (simpler dictionaries) :
- 明鏡国語辞典
- 三省堂国語辞典
- 三省堂 新明解国語辞典
Camp B (broader dictionaries) :
- 大辞林４
- 日本国語大辞典
- 大辞泉
You want to buy more than two :
It’s only after you have already bought more than two dictionaries that I would start to consider Kanji dictionaries, but a thesaurus is a fantastic tool to explore your dictionaries deeper, and I would advice picking one up as soon as you are in the market for a third dictionary. My main recommendation would be 日本語シソーラス 類語検索辞典 as I fall back on that one a bit more, but both picks are quite solid.