1st thing I'd do is set your requirements. What are you using this laptop for? Do you need to run specific software for it? What does that software need to run well. You mentioned CAD, I had a look at the System Requirements for AutoCAD and most of this is very easy to pick out on a spec sheet and as long as you're not picking the cheapest machine you should be fine. The only specifically weird one is the bandwidth requirement for the GPU, but pretty much any chip less than 5 years old should be fine. You can search the model on wikipedia for the bandwidth figures.

As for the whole laptop vs desktop debate, laptops give you portability, whereas a desktop is more erganomic; a laptop can be taken anywhere and as long as you're not using super power hungry parts you should be able to get a few hours out of it without needing mains power. A desktop allows you to place the keyboard, mouse, and screen in a way which is more comfortable for you, but you can't move it.

Either way, you need to set some minimum specs. I'd say 1920x1080 screen (also known as full HD), 16GB RAM, SSD storage.

For buying a laptop, avoid Apple. Their reliability has gone down the drain over the last 10 years with each model having a reliability issue. (butterfly keyboards, dust ingress into screens, STORING THE BIOS IN NAND) and that's before the overpriced RAM cost. Used business laptops are a good deal and can be repaired fairly easily. If you're feeling up to it, many of them can have their RAM upgraded with only a screwdriver. For specific processors, look for Intel Core i3/i5/i7 12th gen or 13th gen or the Intel Core Ultra 5/7 for the newest parts, just check that the processor model number ends in a 'U'. This means it's not going to eat your battery in less than an hour. For AMD, look for model numbers in this format '7x40U' where the x is either an 8,6,5, or 4. These use AMD's latest technology, are more power efficient than Intel and give excellent performance.

For a desktop, don't by from a big brand. HP, Lenovo, Dell and Acer all use proprietary parts which makes fixing these machines impossible and that is only the start of the issues. Smaller builders will use off the shelf parts which can be replaced and upgraded easily. Cyberpower PC has a fairly cheap PC which should run everything even if it's a bit old and ugly here. Just remember, you need a screen, desk and chair.

Choosing a web browser is just an illusion of choice. Almost every browser is based on Chrome (included Microsoft Edge) with Safari merely being a cousin of Chrome ( Chrome's browser engine Blink is a fork of Apple's WebKit used on Safari). The only exception is Firefox which uses it's own. Firefox is pretty good, it's no slower than Chrome and has better extension integrations (no Manifest V3 shennanigans) just make sure you install uBlock Origin.

You'd pretty much be stuck with Windows 11 as an Operating System which is shite. Unless you're willing to have your phone open looking up how to bypass the Microsoft Account requirement and then spend an hour fixing Microsoft's stupid default settings, you'll have to put up with it and all it's awfulness. But there isn't any othe choice, Linux is a pain to setup unless you know what you're doing (I use Arch, I don't recommend any distro for casual use) and will likely not support any CAD programs.