Muscular people look good on T shirts but skinny people look geeky... hence for skinny ones, shirts are the best. I used to wear shirts only. But as soon as i got muscular after a year, i started wearing T-shirts. Lol Please don't look at my oic because it is 3 years older lmao!!
I've some sense of fashion and can tell you only teens would rather T-shirt than Shirt. Long Sleeves shirt gives you more mature look and if you really don't like Shirts go for somethings that has collar like Polo.