in terms of quality, Display Port, HDMI and DVI are the same. all three transfer digital signal to be output on monitor. only diff is Display Port and HDMI transfers digital audio signal as well. DVI only limited to video

VGA is analog signal, which means the video quality is adversely affected by length of cable. the longer the lousier unless you have signal repeater. digital cables suffer no such effects

based on the specifications of GT 240, they only have DVI and HDMI (ignore VGA, they should be obsolete by now).  i would suggest going DVI unless you have built in speaker for your monitor which then you can utilise HDMI more

normally i will suggest Display Port over the rest, cause its a non-patented cable (which means cheaper cable, dont need to pay royalty to use the branding like HDMI, which is why HDMI are rather expensive) supports up to 4K reso unlike DVI and HDMI

DVI max reso - 2560x1600 for dual link, single link max 1920x1200
HDMI - 1920x1080, unless HDMI 1.4 which supports 4K but at 30Hz