These days, I normally recommend on the laptop end a Dell Latitude over a Lenovo Thinkpad, but for your situation specifically if you want a laptop and space savings and the need for greater USB ports, I'm popping into the Wayback Machine a bit.
Buy a refurbished Lenovo Thinkpad T series (430/530 is the sweet spot feature/price wise currently), or Dell Latitude E series (The E5430/6430 models are the sweet spots here). US Micro has a good refurbish program, good prices, and decent warranty. Following these recommendations, you shouldn't have to spend more than $200-300 for a solid laptop built like a tank and easy to repair/upgrade.
Don't get too lost in processor speeds. Pretty much any 2-4 core i3/i5 will be plenty for most anyone. The biggest changes hasn't been so much processing speed as power consumption and battery life for some time now. There's some screaming multi-core processors out there, but they're not worth the premium given that all but specialty high-end applications and games don't need them to run. Even Windows 10 doesn't have much beefier system requirements (beyond RAM/graphics) than XP SP3 and Win7. Don't sweat it, and care more about how much RAM the thing has... that'll be the biggest performance booster. Aim for 4-8GB.
Maybe pay a bit more attention to processor speed these days post Meltdown/Specter patching. I'd also try and push you more towards the T430 due to it having UEFI over regular BIOS on the T420 now, but unless the system is actually set up and the OS installed using SecureBoot under UEFI, it won't do you much good (no refurbisher installs Windows in Secure Boot mode - so if you want this, you'll have to enable it in the BIOS yourself which is a small thing if you're planning to replace the hard drive with an SSD anyway).
The best go-to places for shopping for these things are
US Micro,
Arrow, and
EPC. Aim for Windows 10 Pro as your OS.
Probably cheaper now, but I'd specifically steer you toward a Thinkpad T420/T520 or T430/T530 (even despite the lesser keyboard), or even an X220. Why? USB3/Thunderbolt docking stations stink, I've yet to see one work as well as the older docks, and overall I've seen more problems out of them than not. The older style proprietary docks work better, so older laptop it is, and of this proprietary dock era, I prefer Lenovo over Dell. Of the Lenovo docking stations, unless you wind up with a T430 with an Nvidia graphics chipset or a T530, the following docks should work for all the laptops in question:
ThinkPad Mini Dock Plus Series 3 (433810U)ThinkPad Mini Dock Series 3 (433710U)Find a dock with a good number of USB ports, and/or
add a powered USB splitter to the thing. Shopping for used docks should be straight forward enough. If you don't need the ability to lock the laptop into the docking station, don't worry about getting one that has the keys so long as it's unlocked. Make sure it has a genuine 90W Lenovo power supply with it. When testing it, the laptop should click into place easily, and the eject button should be easy to press - if you have to force it or it's not making a good connection, you likely got a bad dock (it happens). Buy from sellers on Ebay who deal in off-lease computer parts and have multiples units of the same docking station for sale at the same time... just in case. And of course be prudent about who you buy from, but I can't recommend anyone in particular who does keep docking stations in stock all the time.
One last docking station tip if you go this route, make sure the laptop is on and Windows is booted up to the desktop first before you dock it
for the very first time. Do not try to boot it from off on the docking station the first time, it won't work. Once the hardware is installed and recognized, you're fine and can boot from the dock after that, but not before.
If you want a desktop specifically, any Dell Optiplex that you find at a good price from the sellers I recommended and specs/form factor that look decent (Intel i5/i7 processors, probably aim for 8GB of RAM).
If you want an SSD with any of these things (laptop or desktop) given we're dealing with refurbs and mechanical drives, buy a sufficiently sized Intel, Samsung or Western Digital in a 2.5" form factor drive, install it yourself, and
install Win10 fresh
yourself as well. If you go desktop, you might need a
2.5" to 3.5" drive sled adapter as well. You can
write the Windows 10 ISO to a USB drive using
Rufus.
