A wash & cure station for his resin prints would be a good idea of he doesn’t already have one. Mine really stepped my game up & I consider it an incredibly useful utility.
For his Ender I think some utilities like the Mintion Beagle camera or a filament dryer are very useful but also aren’t everyone’s first thought for an upgrade. Good luck!
I have a handful of printers including an Ender 3v2 and a Creality CR10S4, and my experience with Creality printers is that while they are cheap & usually offer nice features they are lacking in quality control & overall quality of the parts used (though the sprite extruder is a beast). If you are willing to put the time into tinkering with them then you can still make out with a decent printer for less than most comparable manufacturers.
Based on the features you listed I think the Qidi X-Smart 3 might be down your alley. The first few months after release were a shitshow with the firmware but now it’s in a really solid place & mine has been quite reliable. It has a smaller build volume than the Ender 5 S1 but can print significantly faster.
If you are willing to expand your budget a bit I’ve noticed that Bambu Labs has dropped the price of the P1P to $600usd/~$800cad. I don’t have any personal experience with Bambu Labs printers & honestly dislike some of the companies practices, but everything I’ve heard about the P1P & X1C has been fantastic.
Huh, I was wondering why 10% of our patrons disappeared overnight. It’s normal for a drop-off at the start of the month but not normally such a large one