Chicken day in and day out is not only boring, but may not be very well balanced. The nice thing about providing variety is that different types of meat (and different cuts from the same animal even) have slightly different nutritional values. Beef and other red meats tend to be a little higher in iron than poultry or fish. Fish is higher in omega fatty acids than other types of meat. Organ is an important part of the balanced carnivore diet because it contains a lot of vitamins and minerals that aren't going to be present (or not in sufficient amounts) in muscle, fat, or other tissues. A cat can eat pretty much any kind of meat a dog can, so achieving variety isn't that hard. Options include chicken, turkey, quail, duck, rabbit, beef, pork, lamb, goat, various types of fish, pretty much anything that's available to you. My cats love their beef and pork, enjoy quail, eat chicken and turkey fine, and are so-so about fish (they can take it or leave it most of the time).