1 vs 1 PVP is BORING! and sometime u dont have enemies.
I suggest to have a Open ARENA wer people can kill one another 24/7 for the price of Arena Rank. (or not 24/7, maybe 8-12hours a day excluding maintenance day)
Open World PVP is just not enough, people are searching for a good time with many other people, NOT just one versus one.
Node War has schedule! -----requires good guild
Guild war has schedule! ------requires good guild
Siege war has schedule! ------requires good guild
and Ramoness SUCKS(searching time is > than battle duration)!