Best dry food for older cats?

[GiantKitten]

Mine are 10, 9 & 7.
They've been on Royal Canin neutered biscuits forever, plus Felix pouches - they always hoover everything up and seem pretty healthy overall.
7-yr-old male (who eats the lion’s share) has gained a bit of weight this year and vet suggested he should lose some; so as the neutered food is supposed to be for up to age 7, and he is a bit more sedentary these days, I thought maybe I should change the biscuits.
Or give more wet food with the same biscuits?
Suggestions, please!

Mine are on Iams. One of them doesn't tolerate royal canin. I swapped them to the senior variety and one of them t
Was so offended by me implying they were old. She got colitis!

@Toddlerteaplease thanks! Iams is the one I keep coming back to, I hope they won’t be offended!
Do you get chicken or fish? (They prefer fish pouches, but the Royal Canin only mentions “poultry” so it probably doesn’t matter.)

Orijen very high meat percentage so they need very little

I get the Indoorcat or the light in fat one, the standard one gave them loose poo. My two will pretty much eat anything as long as the kibble isn't to small. They liked Scrumbles but struggled to pick it up with their flat faces.

I did come across Scrumbles while googling earlier today & thought it sounded ok; Orijen is completely new to me, needing little because no grain sounds good but I wonder if greedy cat would agree…!

I’m thinking I should probably get small packs of all the possibles and try them out (mixing with the RC initially).

They had picky moments in their youth, but not recently, so I’m hoping they’ll be happy to eat anything and it’ll just be a question of seeing if anything disagrees with them.

Mine has Iams senior or Purina one senior