Civ IV and V were quite different in the way they regarded their civilisations. Civ IV gave traits according to its leader and affected how well certain playstyles could be played. In some civs' cases, more than one playstyle was encouraged through the use of multiple leaders. Civ V took a different approach with unique abilities. Now, each civ gets a certain bonus often seemingly based on its actions in real life. For example, Denmark's history as a Viking nation gives their embarked units greater movement. I personally prefer the Civ IV system. Whereas some traits are nearly always better than others (I'd take financial over protective any day) there is at least some use in every trait. Some of Civ V's abilities are very situational, and can sometimes be rendered totally useless. What's more, some unique abilities are clearly superior to others. Japan's Bushido ability is far superior to England's Sun Never Sets for example. Sun Never Sets can be utterly useless on land maps - Bushido is useful in any war. Spain is utterly useless if you don't find a Natural Wonder. Abilities pertaining to city states are useless if no city states are on the map and so on. I much prefer the small, but nearly always useful bonus to a specific but sometimes worthless and too situational ability. I hope Civ VI takes steps towards this again.