Engineer is probably my favorite class to play. I love juggling keeping my buildings online or setting them up. Seeing as I play payload and 5cp the most, the dynamic objectives in those modes means I’m always moving things around and there’s always something for me to be doing. Thus, I rarely find the class boring. It certainly can be boring if all you do is set up and turtle, but you don’t have to do that and I’d argue the game rewards you more for not doing that. It’s much easier to catch kills by putting your sentry in a weird or extremely forward spot if you can get away with it. If you do park the sentry somewhere and then forget about it, you can (and should) still play dynamically with your teleporter and dispenser, since they can often make the difference between winning or losing.
I also disagree that he’s particularly easy. His primary weapon is most characters’ secondary. Shotgun is strong but most classes have something stronger. You’re medium speed and only have 125 health. Assuming you’re maintaining your equipment in a way that helps your team, you’re an important target for the enemy team, arguably the most important behind the medic. Snipers are gonna be out for you, demo and soldier are gonna aim for your gear or dive to kill you, the spy exists, and medics will spend their uber to tear a hole in your defense. As engineer, you’re naturally being pitted up against a lot of different enemies. How you and your equipment are positioned are a big factor in whether you’re at a major disadvantage or have an even playing field in any given scenario. If you play well, you can win almost any 1v1 you find yourself in. This dynamic is another reason I find the class so satisfying to play. Uncle Dane’s How to Fight Every Class as Engineer video kind of outlines what all you’re up against, and I think it’s a great watch.
Your main focus in this post is the sentry, and I think that might be part of why you think he sucks. I’d recommend trying out the Gunslinger (mini sentry) and seeing how that feels to play with. Maybe focus on building teleporters and dispensers to help your team more. The mini sentry and extra 25 health are just kind of a bonus if you play that way. Bonus points for using the widowmaker since it’s a shotgun with infinite ammo if you can aim. That loadout might train you out of the sentry gun mentality since the mini sentry becomes an afterthought.
I don’t know how you can come to the conclusion that most of his unlocks suck other than not having tried them much. With the exception of the pomson 6000, every one of his unlocks provides a cool upside and a balanced downside that completely change how you play him. I find myself changing loadouts regularly between and in the middle of matches. I’m not a huge fan of the rescue ranger, but I’m constantly switching between the stock shotgun, frontier justice, and widowmaker while also switching wrenches depending on the game state. I basically always have the wrangler equipped but I don’t use it as much as some people do, and I have huge respect for the pistol engies out there.
Hopefully my thoughts give you some insight. No shame for not liking him tho, everyone has their preferences. I suck at spy, and am bored to death as medic and sniper. Other people exclusively play those characters and never touch engie.