So i’ve been trying to weight and analyze the gameplay difference with the two most contrastant builds i could come up with on the Engineer.
First: Gadget Sniper (100% Glass Cannon)
http://gw2skills.net/editor/en/?fcAQFAUlIqicnpSiF17IyoHkWnNhgUoX+1HFyVbB;TkAg0Cno4ywlgLLXOukcNIA
With this build you’re doing a single thing. PWNING NWBS. 50% crit chance and 60% crit damage, you can pack “THE” punch against most classes. Light armor wearers can get nuked in 2-3 seconds with your belt only. The burst damage is so holycowish high it’s not even funny.
Key points of the build are low-CD toolbelt skills to abuse Static Discharge trait (which deals a lot of damage) coupled with the trololo Grenade Barrage damage.
The build is flexible to tweaking, but keep in mind the Crit chance/ Crit damage toolbelt- abuse priority over anything.
Pros:
- Hundred Blades-level of facerolling burst damage (beginning of the fight emptying your toolbelt with 10% scholar rune buff)
- Damage
- I said Damage
- Dat critical hit
Cons:
- VERY squishy (kill or die mode, no survivability cooldowns)
- Very poor Control (LOL auto-cc Overcharged)
- Raging QQ opponent because engineer damage is too OP
Second: Tinkering Fortress (100% Survival/Sustained)
http://gw2skills.net/editor/en/?fcAQJAqelIq6ZnvShF17IRoH43wqFUh8K6xjtMlB;TsAg2CrosxYjwGrNObk2M24sxcDA
Dying? Downed mode? What is that? If my life is ever low i cleanse-immune for 3 secs, heal 8k (on 15-sec cooldown if you take the heal turret as soon as you drop it) and go back to fight.
It gets reeeeeeeeeeeeeeally hard to kill you, period. Regeneration, toughness, healing power and downright annoyances makes your opponents who usually focus-fire engineers (because they’re usually offensive-oriented) waste a crapload of time trying to down you (ohhh so you wanna burst projectiles on me? Nicey but you can take them ALL back on your face, thanks. Melee then? Have fun getting stunned then knockbacked then blinded, confused, poisoned and bleeded while i run tiny-sized on my tiny-foots while cleansing and healing a ton of damage)
Pros:
- Three possibly always-on forms of regen (Dolyak runes, Backpack trait, Elixir-Infused Trait) you line of sight and bomb spam for 3 seconds – 2-3k heal already)
- UBER HIGH toughness coupled with 1k Healing Power
- A gajillion condition removal (Formula 409 trait)
- Immobilization-resistance (not the best but handy as sometimes opponent miss your location.)
- Two stun breakers (one giving you invulnerability for 3 secs)
- AWESOMESAUCE REVAVAL (too fun on large group fights)
- Big surprise factor, as your opponents will try to burst you down as quickly as possible thinking you’re squishy and waste their time while you survive a lot of their damage. That gives your team members room to sink damage in their heads possibly winning you control of the node.
Cons:
- Lowish damage and dependant on conditions (if your opponent can cleanse a lot you better find another opponent)
- High skillcap and room for mistakes (you must have good timing with cooldowns or you can find yourself getting bursted while waiting for your stun-breakers to recover)
- As your damage comes in the form of sustained condition over time, you can take a lot of time to kill a target on 1v1 giving your opponent enough time to get reinfocements and getting you overwhelmed.
Sooooo i’ve been bouncing back and forth on total offense and total defense in my games and having a blast. It’s very nice to shift your build completely like that because it keeps the gameplay fresh and prevents you to get boooored. Try for yourself – do 10 games in Glass Mode then 10 games in Fortress mode. You’ll be happy to see the way you can kill faster, then get happier to see the way you not die at all.
Of course you can build a more balanced spec and stick to it but if you like more role-ish builds, this is a winning recipe for fun 
(edited by Drunkwizard.9173)