As you can see, eAthena is 'OUTDATED' anymore if you're still existing to use it, it's your own choice but for me, i can recommend rAthena to use, there are lots of 'FEATURES' like 'Mount System' eAthena does not have that, but there is a 'CODE' that you will add it manually.
You can use Both Pre and Re
Regards,
Mindless