If you don't know that much, how do you expect to use a buffer? What's your level? 10?
no need to be rude, due to everyone ELSE using second accounts for buffers, buffers as a played class are almost nonexistant so some people do not have access to buffs easily.
What buffs WC or OL lacks for an archer DD? Thinking of windwalk (Warcryer), mental aegis, bless body and soul. It takes pretty long time to level them to get max out of their skills, prophets are bit more "useable" on lower levels buff-wise.
since an OL has to be in the same alliance as your main character to buff and heal, and not just party... i can just about guarantee they wont make a good buffer (this is in regards to a second account buffbot-type character only!) warcryer would do slightly better since you wouldnt have to have it clanned to use, however, you would have to keep it grouped to heal and buff... and orcs do not get a ressurection skill. also it would use all or nearly all its MP for 1 buff round, if you were to die or get cancelled rebuffing isnt an option without extra downtime. orc buffers are much better for buffing bigger groups though, these suggestions/opinions apply only to orcs as a tag-a-long-buffer on a second account :P
and for me personally... i would definitely make a prophet over SE for an archer, if your going to use it on multiple classes though i would have to go SE. if your playing your archer properly, heals shouldnt matter because you shouldnt be getting hit. more MP might be a bonus in the SE's favor, but that will only work if you keep leveling it in group with your archer all the time (recharge only works if your recharger is at LEAST 10 levels below the rechargee... it becomes more effective the closer in level you are) both prophet and SE get the same 20% res so thats a neutral point also. so its down to the buffs:
SE gets:
windwalk - increase runspeed
might - increase P.attk
shield - increase P.defense
kiss of eva - increase breathe bar underwater
empower - increase M.attack
focus - increase critical rate
mental shield - increase resist to hold/sleep
concentration - lowers probability of spell interruption
vampiric rage - restores HP based on a % of the damage you inflict
death whisper - increases critical damage
guidance - increases accuracy
resist wind - icrease defense against wind attack
wild magic - increase magic critical rate
Prophet gets:
acumen - increase spell cast speed
concentration - lowers probability of spell interruption
kiss of eva - increase breathe bar underwater
might - increase P.attack
windwalk - increase runspeed
shield - increase P.defense
focus - increase critical rate
mental shield - increase resist to hold/sleep
holy weapon - increase damage done to undead
berserker spirit - increase P.attack, M.attack, Attack speed, runspeed and cast speed while reducing P.defense and M.defense
bless shield - increase shield defense rate
death whisper - increase critical damage
guidance - increase accuracy
invigor - increase resist to bleed
bless the body - increase maximum HP
bless the soul - increase maximum MP
haste - increase attack speed
magic barrier - increase M.defense
resist fire - increase resist to fire attacks
regeneration - increase HP regeneration
resist aqua - increase resist to water attacks
resist wind - increase resist to wind attacks
resist poison - increase resist to poison
you may double check this list of skills here
http://www.lineage2.com/Knowledge/race_human.html
both classes get updates in root, SE gets robe/light armor masteries, prophet gets robe/light/heavy masteries. although prophet does get more buffs as a class than SE, many of those are mostly useless in pve, so dont be fooled. prophet gets Return (self bsoe) while SE gets recharge (mp transfer) it all depends on your playstyle, what you hunt, what gear you use, your class, so many things its hard to say one is 'better' than the other. pick which one is right for you :P