The only problem with these ancient and durable HP Lasterjets - I used to use a 4L - is that they were slow. My modernish Brother HL2270DW - which I got for free at a garage sale because the toner cartridge was missing so they couldn't test it - is much faster and can print double-sided. And has a $20 aftermarket toner cartridge in it.
I used to maintain/repair a couple of LaserJet IIIs (circa 1990), up until about 2010, when I got tired of the printer's footprint being so large, and retired my last computer with a parallel port. The LaserJet III was the VW Bug of laser printers in terms of being easy to repair.
We used old HP Laserjets in a warehouse up until about a year ago. Towards the end, we had to repair and replace them with increasing frequency due to the beige plastic becoming very brittle. As a result, the printers became hard to service and more prone to damage during regular use. Replaced with a cheap Brother laser.
People were buying second-hand 1995-era Laserjets in 2010 because they were simply better than anything you could buy new. They... Just Worked.