I don't think this can really be considered without also thinking about the skills each of these atts offers. Rankings are in terms of 3 tiers, 1st being best.
Soul Reaping: Certainly godly in PvE, less useful in PvP. The fact that this line ALSO has signet of lost souls makes it truly great, as those spent att points give you a ton of extra energy (in PvE) as well as access to an energy+health gain costing no energy.
Ranking/Suggestions: Top tier attribute for PvE, 2nd tier for PvP. No big suggestions, but it would have been nice to have more skills in this line.
Expertise: Truly a powerful att. The energy reduction of ranger skills, as well as touches, spirits, etc. makes Rangers a force to be reckoned with. In expertise there are skills to interrupt, block, inflict blindness, further reduce energy of bow attacks, cheap spammable dmg skills, and IAS, run skills. Just about everything you could want, all tied to an attribute you'd already wanna put points in anyway.
Ranking/Suggestions: Top tier attribute for both PvE and PvP.
Critical Strikes: Inherent extra dmg, energy gain and a host of reasonably valuable skills. Also you the ability to block an awful lot (with critical defenses) as well as the ability to inflict a lot of conditions, although most of them are more useful in PvP (i.e. cripple, etc.) Also offers IAS, but only through an elite. Worth noting is that this primary is only really useful when attacking, and sins have low armor for a front liner.
Ranking/Suggestions: 2nd tier for both PvE and PvP. Would be top tier if the line offered some slightly more useful skills... as currently most of the skills only enhance the attribute itself.
Divine Favor: More healing is useful, but often results in over-healing. Very important for PvE farming, offers some useful skills in general but most of them are elites. Offers some limited form of energy gain, but conditional on the use of signets or maintaining enchantments.
Ranking/Suggestions: 2nd Tier for PvP and PvE. We have seen that divine favor isn't needed for a good healer if energy is readily available. This line offers little to no energy management, but does have some nice elites to complement other monk attributes or for farming.
Energy Storage: Offers a boat load of extra energy. That in itself isn't that big a deal as many ele skills are fairly expensive. However, this has a great deal of utility as well with skills like Glyph of Lesser Energy and Ether Renewal. So has good energy management and some decent self healing. Very little damage to speak of, but provides for good survivability.
Ranking/Suggestions: 2nd tier for PvE and PvP. The energy management of Energy storage is awesome, but it would have been nice if it offered ways to remove exhaustion or ways to decrease cast time of spells.
Leadership: Offers nice energy gain when casting shouts, as long as you do so nearby as many ppl as possible. Also offers an VERY nice IAS which can be maintained almost indefinitely. The ability to inflict burning coupled with the ability to reduce damage taken from burning foes is very nice as well. Also offers a good repeatable res, forms of very good party support and the ability to become an imbagon in PvE. This attribute makes paragons one of the most godly professions in the game.
Ranking/Suggestions: Top tier for PvE, top or 2nd for PvP. The party support of a paragon is immensely helpful, but having unlimited energy/adrenaline makes you able to drastically increase party dmg and survivability.
Mysticism: Offers decent energy gain, with some health gain thrown in. Enables the use of avatars which can be fun. Skills offer a decent dose of self healing, and energy gain. Also contains the derv's best IAS, and the ability to inflict/extend a few conditions.
Ranking/Suggestions: 2nd tier for PvE and PvP. Would have been nice if this line contained some of the utility of expertise, such as blocking.
Strength: Offers extra armor penetration, which can be quite useful, but often isn't. Line offers some impressive stuff, such as good IAS skills, good run skills, Bulls Strike (for PvP) one of the better self heals for a warrior, extra armor, temporary health gain and some reasonably good attack skills.
Ranking/Suggestions: Top/2nd tier for PvP, 2nd tier for PvE. Warriors are damage dealing machines, and strength is one of the best complimented attributes for that purposes. Still, the lack of things like hex/condition removal limits your options and can force you to spec into other attributes.
Spawning Power: Offers the ability to make meatier spirits/minions and extend weapon skills. Line offers the ability to remove conditions, cause dmg on creation of spirits/minions, reasonably good energy management and a very nice elite (Consume soul). Overall pretty underpowered, but only because spirits and weapon spells are outpaced by other forms of damage.
Ranking/Suggestions: 3rd tier for PvE and 2nd/3rd tier for PvP. The use of spirits generally declines as the game progresses. Only the party support spirits retain some usefulness, but those generally have low duration even with lots of spawning power. While the line does offer some nice incentives for a minion bomber, N/Rts can generally perform this function better. Unless spirits and weapon spells become much more powerful, this attribute will be underused (for very good reasons).
Fast Casting: Offers the ability to decrease spell and signet activation. Does not affect glyphs, binding rituals, etc. Skill line is a little light, but offers the ability to steal and use another foe's elite, and to recharge spells faster.
Ranking/Suggestions: 3rd tier for PvE, 1st/2nd tier for PvP. Many mesmer skills seem to have been desiged to have long cast times, probably because fast casting was thought to solve that problem. While the line does offer nice abilities, the lack of energy management forces one to spec into something like inspiration, leaving fewer points for more important attributes. In PvP fast casting can make a big difference, as interrupts/hexes/debuffs are more important than in PvE.
