Option 2 is the best imho and it's the one I use all over.
If you have categories then using the category/post title is gives you more keywords for ranking in the serps which has worked for me.
If you dont have categories then using the post title is the best option.
Keeping them like this make them look more professional and search engine friendly.
I personally like option 1 (personal preference), but I believe option 2 is best in regards to SEO.
I'll go with the option 2.
It appears that I cannot use the /postname option. This website I'm creating needs categories, which are featured on the homepage. If I use the /postname option, the categories don't work. Therefore, I have to go with the /category/postname option.