Anecdotally, we had the opportunity to get better gear for developers than an outdated single 24” 1080p screen and slow computer. Higher management invited a few engineers to share Ygritte ultimate setup. These varied widely between one large ultra widescreen and three small screens. The developers in the meeting started arguing vehemently in the meeting and in the end they couldn’t agree and all developers were left with the same stuff. If you were enterprising enough you could gather two of those 1080p screens until someone from workplace it saw that and installed to desk to spec.
It was a mistake to give an option to discuss this to start with. It's always if not this than that, x brand is better than y,etc.
What matters: is it a Windows/Linux/Mac shop?
No matter what brand,the base unit comes with enough RAM,
processing power and spacious SSD.
Everybody gets the same brand,as it's easier to support from the IT perspective.
Keyboard,mouse,monitors should be an individual choice. Some want to ruin their vertebrae by staring at a tiny 13" screen and be happy about it,while some need 3 monitors and 2 keyboards to feel the power,why not.
Not sure why some companies are so tight when it comes to the equipment for developers,as it's always a small fraction of the overall cost of the position.