Short and sweet answer...
I want: The 2007 release server which means i don't want poop like xp boosters... I think thats a simple answer
But for those who like to read, a more indetail answer...
P2's would be nice (not maxie) +10-15 armor max as the original was like +4 then +10 for the max upgrade. I would like to see the old PvP redname system etc put on the server so that people who pk get punished... and people who save the city from the evil get honoured by blue names (could add special titles and abilities for those who do good and maybe give the sinners a lump of coal
or something) promote Blessed Iris & Elixirs/XP pots as thats all we had way back when... not PBI's or boosters (except IDB as those make life interesting trying to obtain the gear you want). I dont want to see cast pots, i want to see the return of GM gear raffles, although perhaps f2p type raffle events not buy "x" amount of something. No need for master stones (unless you do as before and make an item upgraded with master stones not tradeable) the old costumes covers like the fish bones for the duals etc... would be nice to have back for some fun... bring back things like the old jap sets for a change (maybe a revamped higher lvl version), i dont want to see things like Stone of Shadow, Tears of Kight etc.. added in as when they were released it changed the game, however perhaps some new things similar to blessed chords green stones and the like could be a good idea...
And the biggest point i would like to note would be... make it party friendly, and balance all the classes (elementalists, clerics, witches mainly so that all do equal amounts of damage in a party and all can have support buffs of some sort) this would enable people to enjoy their gaming experience and help others enjoy theirs too, as solo leveling is not fun.
I miss the good old Orcs, Highlander, Gnolls, Giant Larva parties... and some of the other long lost monsters. (Fun times when Death Knight of Iris spawn cards were released into the item mall hehe those made good spawn parties, perhaps you could keep oscar books in it too for people who decide to gain the affinity, so that they can have guild monster spawn events or something similar)
Anyways rest period is over
have fun, and yes i know its not exactly adhering to your rules but hey ho lifes not always that simple
but i did give a short answer too