I don't remember what kind of problems Steve had back then, but at least nowadays I think you can find decent ones.
The most popular is probably Naver's dictionary https://endic.naver.com/ (Naver English at LingQ). I remember that I started out using Daum's dictionary but now I like the interface over at Naver better. Especially how you can switch between English, Korean and Hanja.
If you are interested in Hanja, I can recommend: https://koreanhanja.app/한
Thanks for the answer pal! This is great ^_^. I will try out this naver dictionary :)
With regards to Steve, I remember in his 90 day challenge, one of his issues was that he struggled to find a dictionary that gave him clear definitions, and trying to work out what the word was in that context just took a long time (compared to Chinese and other languages)