If you're interested in buying secondhand laptops, I strongly recommend you look at any "business-class" model from any manufacturer. Laptops that cost $1,000+ and are aimed at business fleets, rather than individual consumers. These laptops tend to be very well-made, are designed for commonly-broken parts to be easily replaceable, and are widely available secondhand as companies update their laptop fleets. Here's an incomplete list of manufacturers and series:

* Dell Latitude (except the budget 3xxx models) and Precision * HP EliteBook and ProBook * Lenovo ThinkPad X, T, and P series (in order from small & light to big & powerful) * Panasonic ToughBook (rugged!) and Let’s Note * Fujitsu Lifebook * Acer TravelMate and Extensa * Asus ExpertBook * Toshibe Portege and Tecra * Epson Endeavor

To harp on avhon's point, ThinkPads have specific lines where most parts are made to be easily replaceable: the RAM, SSD, wi-fi card, fans etc. are user accessible. Not all ThinkPads do, so you need to at least care about the line (X, P, T, E, etc., it's a whole world), and check the repair guides and community reception.

Panasonic also has a stellar reputation in that regard.

Bear in mind they will break and you'll be hunting for parts, it's just a lot easier and viable than some other laptops.

I bought that specific model because they're a step up from the E-series (which is actually good now), but not as expensive as the X or T series. I'm very familiar with Thinkpads (I personally have owned 5, and have bought 3 for family, all used, all functioning perfectly). That specific model does not have soldered ram, has lots of replacement parts, is still fairly new, I'd owned an L14 Gen 1, and to be honest, it was just a good deal considering it was in mint condition.

With thinkpads, assuming you're buying used, you can pay the premium for a T or X series, and get a laptop with essentially the same parts, but maybe a better screen or chassis, or you can save money and go with the L or E series. NB, the T and X series oftentimes have soldered RAM, so if you're not satisfied with the amount of ram already in it, do your due diligence to ensure that the model support using SODIMM/replacing the ram.