For those who want elite tombs only, here are the easiest bosses

Some people may have hard time selling greens, that is because most greens are easily farmable or it is just to common. For a decent money maker, you can farm elite tomes (most ppl want those for skill hunter track, especially some elites are difficult to obtain). If you wish to farm elite tomes only, here are a list of the easiest bosses you can farm for those elite tomes (note: the greens that drop is either have low value, or have a high sell value, just hard to sell them). All the bosses can be farmed with the Shadow Form boss farmer and details, check the link (except for the Paragon boss, it can done with the Rt/Me Farmer in HM easily, the ranger boss could be farmed easily, but I haven't tried it yet):

Warrior: Chor the Bladed
Ranger: Zelnehlun Fastfoot (requires lots of good timing, and there would always be ntoukas in the path using [skill]Intimidating Aura[/skill] which can strip Shadow Form while trying to run past them, so use cover enchantments).
Mesmer: Eshim Mindclouder
Elementalist: Birneh Skybringer (number of queens can screw you over, bring elemental lord and get the blessing that increases your earth magic should do it), Korshek the Immolated (long run, but rez shrine is relatively near him, bring Recall), Kormab, Burning Heart (enter from Wilderness of Bahdza, it's easier, and bring Shadow of Haste. If happens that there is a Diamond djinn, rezone, because of [skill]Angelic Bond[/skill].
Monk: The Scar Eater (wait till the patrol in front you get close to the boss)
Necromancer: Sessk, Woe Spreader (sliver may sometimes have a tendency to target the warriors instead, so you might need to bring Shadow of Haste and a cancel stance when that happens).
Assassin: Xuekao, the Deceptive (bring shadow refuge, grab very nearby shrine, and let Am Fah kill nearby Jade Brotherhood as well as yourself, because you dont want the Am Fah follow you to the rez shrine, it can be done with death penalty), Darkroot Entrop (the daggers he drop is so and so ok, i doubt anyone would buy them), Chimor the Lightblooded (requires some good timing and patience. the daggers he drop is quite good and sells around 10k-15k, but it's difficult to sell)
Ritualist: Tomton Spiriteater (first group of yeti within the ramp/cliff like area can be easily avoided and unaggroed, make sure you aggro all yetis near tomton and NOT the wallow, which they have skills that bypass shadow)
Dervish: Fahralon the Zealous (fighting her can be a bit tricky, she can do 400+ damage with mystic twister. Bring armor of earth, dark escape, an AoE spell, shadow refuge, and feigned. There is a group of shadow army folks once you enter the area so watch out.)
Paragon: Hassin Softskin (he the easiest boss to fight and can only be done with vengeful farmer. For those who are going for sunspear track, make sure you kill 25 insects before facing this guy).

The bosses listed here are the easiest to farm, although i did give you multiple of them for the heck of it.

P.S. If there is anytime you have to run pass a bunch of mobs to reach the boss, be sure to active shadow form and use dash, dark escape isnt strong enough since the foes run faster than you.

P.S. elite tomes are incredibly rare. When I farmed scareater, I got 17 so of his staff and only 3 elite monk tomes.

I almost forgot, if you are facing a boss that melees, you do NOT need to shadow step. they WILL come to you (sometimes fahralon gets body blocked, which is annoying). If it happens that there are more than three melee foes, attack him so the boss would say "This is bugging me, I ain't leaving." In other words, the melee boss wont flee went you literally attack with your weapon.

for monk i would say

Outside of Cavalon in Archipelagos

http://gw.gamewikis.org/wiki/KaySey_Stormray
then go to
http://gw.gamewikis.org/wiki/Ssuns%2C_Blessed_of_Dwayna

its best because theres 2 monks close to each other and close to an outpost

Also, for an easy monk boss farm see:

Byzzr Wingmender

One of the easiest farms with the Ranger/Mesmer famine build.