The Siyam Rupali font developed under the Avro Free Bangla Font Project is the best Bengali font I have seen. There is really a dearth of good Bangla font. The ‘matras’ of Bengali letters make the fonts look very small thus compromising readability. Siyam Rupali font, a modified version of Rupali Bangla font with hinting by Md. Tanbin Islam Siyam, has come over this problem and looks great on screen. Say for example, you can use this font while chatting on a messenger – there won’t be any problem of ‘small font size’.
You can download it for free from the Download section of my site. I highly recommend this font.