I have always been impressed by the Case machines, and have owned 580 super K and 580 super L, as well as ran a 590L. The 590L was everything the 580's were plus much stronger and more stable.
I have also owned Cat 436, and thought it was a POS. It spent as much time broken as digging. I demoed new Cat hoes when I bought the 580 Super L. My worn out super K would outdo the new Cats in everything except comfort, and that was because of comparing new vs 8,000 hrs.
At the time Deere or Ford/New Holland was not an option for me due to no dealer support.
For most tasks the Cat was fine, but the Case would do production digging faster, set heavier pipe, and lift with the front loader loads that the Cat would not even think of. When I had the chance for a 590 for a while I was very impressed with the strength, though it came with a slight reduction of speed on the backhoe.
My Case 580's would dig with a 36" bucket, extendahoe all the way out to reach 14' deep utility vaults, and cycle fast with heaping buckets. When I tried digging vaults with the Cat, I had to either go to no larger than a 24" bucket, or else pull the extendahoe in all the way before lifting the boom out of the hole.
Cat does have more power in the boom lift than Case, due to the bent boom, but the Case will still lift more if you boom up first then use the stick for lifting. The Cat does ride worse due to the boom design, while the Case rides better when roading due to the over center boom design. In my opinion a Case without ride control rides as good as a Cat with ride control.
In tough conditions like muddy spoil piles, steep hills, etc, the Case would be able to pull with the tires and hoe to get through, while the Cat struggled, robbing drivetrain power to work the implements.
These are the reasons I would go with Case, and a 590L in particular.
I have heard good things about Deere, but have had no personal experience to compare.
I have used new Cats up to current models, and while the newest seem to be smooth and easy to operate, they still do not seem to have the power I had with my Case machines.