I was doubting to write the next one. Since it's obviously not a "product", but want to mention anyway.
My wife. She really completed me in such a way that it significantly improved my quality of life. She holds the mirror in front of me at the right times and works in an entirely different field, making her a great sparring partner.
* Laser eye surgery in 2009 - I know it isn't really a "product", but it is one of the best purchasing decisions I've made.
* Kindle - it is so much more convenient than reading or collecting physical books, and with the e-ink screen doesn't detract from that "book feel" for me
* Tretinoin - this might be a weird one, but as someone who is very into skincare this single product makes me feel confident that I am effectively taking care of my skin for the long term. I don't have to worry about if I'm "doing it right", or bother with gimmicky expensive "texture-enhancing" or "anti-ageing" or whatever-the-next-buzzword-is products. Tretinoin has a very large body of research behind it. We know it works. A single tube of tretinoin (coupled with sunscreen!) saves me a lot of wondering and money. This is not to say I use nothing else at all, it's more like this one product and the knowledge base we have on it keeps me from spending money on otherwise expensive skincare that I don't need, which is _marketed_ to do the same thing as tretinoin but isn't actually shown to work like tretinoin is.
I can't remember exactly what my deficiencies were at the time to be honest, other than I could not see well far away. I was told I needed glasses but never bothered wearing them or paying attention to my sight other than knowing it sucked. When doing an eye test for my driver's permit I was one line away from not being able to legally drive without glasses, if that gives you any idea.
Now there are apparently other options than LASIK which might work better for some. For example, a few years ago a coworker of mine got a procedure that he described as them basically inserting a lens into his eye instead of resurfacing part of the eye itself. Apparently it means if his eyesight changes sufficiently over the years he can just go back and get a new lens inserted!
The bad ones DoS my brain with pointless information, greatly harmed my focus and ability to think, as well as gaming abilities. It's also made driving, especially in heavy rain, difficult and hazardous.
The good one made life seem really high resolution. It reduces eye strain a lot, which is wonderful when you work with computers a lot and live in a sunny area.
Sennheiser PXC-550 - One of the best wireless headphones out there. I can keep them on 8 hours a day without any stress.
Keychron K2, just a well-thought wireless/wired mechianical keyboard. Less fatigue and more confort, I can type 4x more text now.
I've been using these every single day for years now.
Safari Online - Getting learning material has never been so easy. Actually learning all of them is different :)
AWS - I can get hardware resource without lengthy PO and approval.
Wireless Headphone - Apple Airpod.
A fully stocked and well equiped kitchen in the apartment
* My desk whiteboard - It helps so much when confirming/working out a solution.
* My wireless mouse and keyboard - They fit my hands and I can put them away when the whiteboard is what I need.