- High level Fractal : My main is a Grenade Engineer (300+ hours play on it) and i prefer my Guardian, Mesmer and Ranger for that. I'm good with aiming my grenade but while dodging agony circle and mobs you can miss some and you rarely gonna use the 1500 range of your grenade in fractal.
Oh definitely Guardian at high lvl fractals is just, too good.
Followed by mesmers, and then elementalist and perhaps warriors (the GOOD ones). Due to the large health pool, large numbers, and one-hitter style of the mobs in later fractals, high aoe damage (preferably ranged) would be very useful, that means basically either elementalist or grenadier engi, having one in your team makes things a lot easier. For example: urban battleground mobs, cliffside events, underwater kraits, Grawl final boss, while any professions can take care of those in early levels, in later levels (40+) having an aoe specialist vs not having one makes a big difference. Also, engi makes Asura fractal a lot easier with hitting harpies below their platforms as well as the skipping.
And I have to say, having played 600+ fractals, at 40+ a group with 2+ thieves or 2+ rangers in it often makes things very, very difficult. A GOOD ranger and/or thief can hold his own provided he's the only ranger/thief in the group, but a mediocre one (doesn't even need to be bad, just mediocre) just provides too little, especially ranger. One in a group is OK, 2 in a group is too much, they're taking the spot of potentially a guardian/mesmer/elementalist. You may say "well just get 2 guardians if you have 2 rangers to balance out the utilities", but then you'd have too little aoe dps --- Think grawl final boss, even with 2 guardians chaining projectile reflects, you just can't kill things fast enough. Unless, the last spot is an elementalist or grenadier, AND all the players are very good.
My engi is the first of my characters to reach 40+ fractal way-back-when, and I think any engi who can manage to grenade all the way to higher level fractals has enough awareness/skill already, you know, since your fingers need to have extra strength to run/aim/throw/dodge at the same time with 1 second reaction window. If you've managed to succeed glass cannoning all the way to high levels, you should be good enough for the levels after that. So between a random ranger and a random engi applying to my group, I'd pick the engi for sure, due not only to the things that they can do but also the "security factor" regarding awareness/skill. Well, but of course, you can't really be choosy in higher levels, most of the time you just cross your fingers and hope that the ranger in your group knows what an axe is...