Browsing WordPress forum, I came across a few nice themes that I may consider using in the future. Tarski and Dkret3 will always be the themes of my choice. Both are well designed, with the former more suitable for serious topics and the later for more casual writing.
The first one in the ranking is dfblog . It’s clean but not plain.
Atahualpa from bytesforall is also nice. Its author also makes other themes.
Simplixity is an ‘everything is gray’ theme by a 22 old U.S. guy. The theme is mostly in gray color.
Cleanr focuses on typography. Big fonts lets your users find it easy to read even from a distance. Cleanr focuses on space. It always looks better when you have some space around you.
Big fonts and spaces are always the main reason for me to modify a stock theme.
Other themes to consider:
A promotional theme called Free WP Premium Theme. I am wary about these premium stuff, but this theme looks good.