Flexbox is probably the simplest…you can use your existing CSS and just add
display:flex to your rows (sections in this case)…and, bingo equal height.
This is nice because you have a fallback in case the broswer doesn’t support flexbox.
CSS Tables are a little trickier as margins are off etc. Support it better (IE8) but the extra work (and possibly extra markup) probably isn’t worth it.
Of the two, flexbox is the future…and support is pretty good.