Hello Danielmak,
Probably the most cost-effective and best iPad would be the 9th Generation iPad sold on Apple's Certified Refurbished website (there are plenty of keyboards available for this model as well on Amazon):
Refurbished iPad Wi-Fi 64GB - Silver (9th Generation) - Apple
Or if you want more storage:
Refurbished iPad Wi-Fi 256GB - Silver (9th Generation) - Apple
This iPad has repeatably been ranked highly by Consumer Reports and Amazon customers, and for good reason. I have had both the iPad Air M2 2024 and the iPad Pro M1. Both of these devices were overkill for me, so I eventually sold or returned them. For me, I didn't even use half of the 128GB of storage that these devices came with, so 64GB should be plenty for most circumstances. And I even was doing architectural projects and taking plenty of notes. Also, I used the iPad mini 3 on several occasions and it is remarkably capable!
If you feel like this won't cut it, that's fine. As a rock-solid alternative, the iPad 10th Generation may be the next best choice, or even a refurbished iPad Air M1 (a great laptop replacement):
Buy iPad 10.9-inch - Apple
Refurbished iPad Air Wi-Fi 64GB - Space Gray (5th Generation) - Apple
Bear in mind: while it may seem like, according to reviews and other people's impressions, that these iPads are not powerful or modern enough, it is very rare that you will be disappointed with your purchase. Whether you get an iPad 5th Generation or an iPad Pro 2024 M4, you will still get used to the device and you will have to find out how to use it as a tool in your workplace.
Let me know if you have any more questions.
Have a nice day.