For cost FF and Wellness are about the same. Wellness does have more calories, although the percentages of protein, fat and moisture in the two are nearly identical (not as fed percentages):
How they break down is
Wellness - $.18/oz, 40 cals/oz 10% protein, 5% fat
Fancy Feast - $.17/oz, 31 cals/oz 11% protein, 5% fat
Friskies - $.07/oz, 31 cals/oz 10% protein, 5% fat
They are all "not more than" 78% moisture. I tossed in Friskies because that is what I feed, mixing in a little Wellness or Authority for "better" quality. I feed about 6-7 different flavors, but more often the Poultry Platter, which I just was surprised to see had turkey as the first ingredient, not "poultry by-products". But a lot of flavors have some fish in them.
I think the big difference between FF and Frisk is the carb content. FF tends to be 3-4% if I am remembering correctly and Frisk is 7-8%. Wellness must be low, like 3-4%, right? I wonder why there is such a big calorie difference?
How much does he weigh? General rule of thumb is to feed 13 cals per pound, plus 70 cals - so a 10 lb cat would need 200 cals. But an unregulated/newly regulated cat will eat up to twice as much until they figure out they are no longer starving. Both of my guys lost a lot of weight before dx. Beau went from 16+ to 10.5 (he should weigh 12) and Jeddie went from 13 to 8.25 (he should probably be 13-14 as he is part Maine Coon). They both ate a lot of food at first. Beau ate 9-10 ozs and Jeddie probably close to that. Now they eat 5-6 and 6-7, respectively.