These reviews and suggestions come out of over 1700 hours of playing engineer in all game modes. They will only comment on utilites that do not see frequent use in PvP specifically and recommend changes to put them on par with other utilities for greater build diversity.
Elixir H
This healing skill is pretty good as it offers a defensive boon after casting it, however the swiftness that you a chance to gain is pretty useless as engis already have many sources of swiftness. A better boon in place of it if not removing it completely would be vigor.
Med Kit
This skill, I don’t see taken at all because it’s simply inferior, the only reasonably practical use of it is to drop a plethora of bandages before a fight begins to setup a fight that goes in your favour for healing given you move around. To put this utility on line with other healing skills, I would recommend activiting the Kit remove stuns and crowd control effects such as fear, cripple and chill, though the latter may make it too strong, but at least as a stunbreak so a player can actually get a use out of the 1-5 skills. Another improvement would be to reduce the cast time for the 1-5 skill as it is not practical to have a cast time on such small heals. Also the #4 given the long cooldown should remove 2 or three conditions rather than just one.
A.E.D
Not very often used, though the uniqueness of the skill gives it merits for more offensive static discharge builds. A longer range on the toolbelt skill would go a long way to making it more useful.
Turrets in General
Not much to say here, since I don’t run them unless I’m going static discharge, if turrets were to be buffed though, the toolbelt skills, which are already strong as is other than for the flame turret would probably need a damage reduction or cooldown increase. Not really sure what to say about the flame turret, perhaps a longer duration on the aoe from the toolbelt, and better reactivity with the smokefield.
Elixir U
Rather than gambling on the side effect you want, a completely new one might be favourable as the RNG can really be devastating if you get unlucky gambling with it. Perhaps the sideeffect could be an increase of all active cooldowns by 30%.
Throw Mine
This utility is pretty strong toolbeltwise for high risk power builds, however the utility itself could use a bigger radius for the blowback and perhaps two or three boons removed rather than simply one. Other than that it is still decent.
Flamethrower
I don’t usually use this, but the #4 could use a bit more duration on the burns and autoattacks could do with reworking. The 2,3, and 5 are solid though.
Personal Battering Ram
A personal favourite utility of mine, the toolbelt is decent as a 6 second cripple is no laughing matter, however the utility could do with a slight range increase as well as some other effect to it. If it were unblockable or applied a few stacks of vulnerability, or both it would go a long way to having the utility with the best animation in game see some love.
Elixir C
This skill while good already, could greatly benefit from not having a cast time, thought it might put it over the top.
Slick Shoes
This is honestly a good utility, the only qualm I have with it is how hard it can be to land the knockdown.
Elixir Gun
This kit is pretty solid, however the #3 skill is fairly useless as the conditions do not last long enough to justify using it even in a teamfight unless against a heavy condition based team, to make the #3 better, removal personal conditions as well as teamate conditions would make it a skill to actually use in practical situations.
Mortar
Instead of being something the player has to stand still and fire, perhaps it can fire on it’s own, preferring to target those the player has targetted, and have a second activatable function which fires the #5 skill when the player wants it having a ground target option as well.
Elixir X
I honestly like this utility but it is hardly ever used and could use changes, though I don’t quite know what.