I have seen similar threads to this where people would post their most failed kanji, and I did a search but couldn't find if there was one for vocabulary so decided I'd go ahead and start one. If there is an old thread then the information there might be outdated so no harm in starting another. Feel free to give an explanation as to why you think your most failed words are particularly difficult for you! If you don't know how to find your own, just open your Anki deck, go to the card browser (B) and then sort by Lapses.

I'll start us off with mine: (note that I don't suspend/delete leeches)

1. 戒める （いましめる)  - I get this word confused with 諫める (いさめる) ALL the time.

2. 凝らす （こらす/こごらす) - I often forget whether it's こらす or こごらす and would get the meanings between both mixed up a lot. I haven't had issue with this word lately but I did for a long time.

3. 退ける (しりぞける) - One of these days I'm gonna sit down and really learn the differences between のける どける　and しりぞける (all 退ける), but until that day comes I'll continue getting this wrong.

4. 労る (いたわる) - Yeah, I just keep forgetting the meaning of it because it means a few different things. I've seen it in more contexts lately and that's helped it stick.

5. 観照 （かんしょう) - I often confuse this with the meaning of 鑑賞/観賞. It isn't an issue with other words, but for some reason with this one in particular I can't tie the kanji with the meaning even though it's pretty clear they can be related.

I wonder if there will be any commonality between learners and what words they struggle with. It'd be interesting to see all of yours for some comparison.

My 3 most failed cards are kanji: 詫, 揖, 堕

Most failed vocab:

1. 縺れる - at long intervals blurt out まつれる, confusing it with 纏わる at #5

2. 掠める - this card has only been active since May and has already shot to #2 because of 眇める

3. 善人 - also a young card with lots of early fails because I seem to have formulated a rule that for words like this, good things tend to be じん, and bad things にん (the charitable view). This one not only breaks the rule but じん seems to trip off the tongue more readily for this one.

4. 覆す - used to blurt out おおす because of 覆う

5. 纏わる see #1

Most hated cards at long intervals albeit with slightly fewer fails to date than the above:

3. 戯ける - blurt out とぼける at long intervals presumably because same okuri as 惚ける similar sounding. So annoying.

2. 顰める・蹙める・嚬める - Seriously wtf.

1. 疎む・竦む - I got so pissed off with this one that I edited the cards to include both words both ways round. This one is so frustrating because I have clear mnemonics for the kanji and never fail those, but just blurt out the wrong reading on the vocab.

1. 駆使 (くし)
2. 輸出額 (ゆしゅつがく)
3. 添加物 (てんかぶつ)
Just somehow can't remember, don't know the reason.

I also have problems with 縺れる and 纏わる...