I've got and extensively used both a karrimor delta 35 and a 5.11 rush 24. The Rush 24 is, to be honest, supremely better in most aspects, but is nonetheless heavier and a touch more fussy. It would definitely get my vote though, but that's not to say the Karrimor isn't excellent, its just a little outclassed by the 5.11 being an immense daysack.
The 5.11 has a lot more compartments, and has more of a defined form/structure on your back. The main compartment also unzips deeper so it is easier to delve into the bottom of it. If you do go for the karrimor, the delta 35 is much closer in capacity to the rush 24 rather than the Delta 25.