I am fairly hardcore member of the Moneysavingexpert forums so I did some research into value-for-money wet and dry foods!
Not sure what your budget is or meat content you are after so here is a selection:
Jollyes Lifestage ~£2 per kilo 26% chicken
Burns chicken and rice ~£3.60 per kilo 36% chicken
Pets at Home Purely ~£3.40 per kilo 40% meat
Fish4Cats ~£3.90 per kilo 70% fish
You might also consider Hills when it's on BOGOF (normally £5 per kilo) depending on the variety ~50% meat.
I also notice that you are feeding pouches, which can be quite an expensive way to supply wet food when you are a multi-cat household. Some of the best value are:
Feline Fayre large 400g tins 70% fish (currently 49p Asda, ~£1.20 per kilo)
Feline Fayre pouches 60% fish (£1.90 for eight, ~£2.75 per kilo)
Pets at Home Purely medium 156g tins 50% fish (44p or £2.75 per kilo)
Bozita 360g tetrapacks and large 400g tins ~90% meat (online <£1 each, from £2.20 per kilo)
The final option is to add in some raw meat if you cats will take to it - some people are getting meaty bones and offal free from a friendly butcher, or Value frozen chicken portions are only £1.40 per kilo!