Similar combat/skills etc...I'm kinda surprise no company haven't copy Rohan style yet since IMO it's one of the best mmo i've ever played because of the combat and skill system.
To bump Rohan an MMO has to provide the following two things :
1. Open world pvp with no regulation beyond level requirement.
You reach a certain level you become fresh meat for pvp. No escape.
2. Player-driven economy
A large part of the Rohan experience is its player-driven economy where players can buy & sell almost any in-game artifact up to and including the characters they have built. Very few (none?) games provide this. This aspect is totally ignored by many pservers and those that don't die very fast.
Beyond those two things Rohan offers very little to compete with other MMOs.
Some have far better skill and crafting systems than Rohan. Some worse. Rohan's character customization is one of the worst available on an MMO. Lwet's face it - except for hair color and some minor face differences every single make dhan looks like any other male dhan. Same goes for any other race. Evolved dekans are even worse -- you get 7 variations on evolved dekans and that is it -- you can't even tell make from female for ***'s sake.
No, the no-holds-barred PVP and lively player-driven economy are what keeps Rohan alive and nothing more.