You are debating between two very good mowers. My decision would be based on factors other than what the brand is. You need to go with a dealer you are comfortable with, and you need to demo each unit. Controls and ergonomics are different, you have to get one that you are comfortable riding on.
Good comparison is I have a scag wildcat 61" cut. Dad has a very similar bobcat 223. There are things I like better about mine, and things I like better about his. All my controls are on the left side, his are on the right. Just what you are used to. My scag has pretty heavy shocks on the control levers. So they have alot more resistance to moving. His take no effort. Easier on the arms, but more difficult to hold straight IMO. Mine has much wider front wheels. Thats a big plus in soft ground. And probably the largest difference is deck lift. Mine is foot operated, which I like cause I can feather it if ground is uneven. His is hand operated. But by design and mechanical an advantage, Mine is considerably more difficult to lift for a female.
I know these are two completely different mowers than you are looking at, but just giving you an idea of some of the ergo differences. You really need to try out both of them, and make a decision based on that and the dealer, rather than the brand of the machine.
And as far as 61" vs 54" deck. With only 1.5 acres, you should be able to have that done in 30 minutes, which is a reasonable demo time. Mow your whole yard with the 61. IF you have any problem areas or scalping issues, maybe try the 54" model of the other brand the following week. Then bick the brand you liked best, with the deck size you feel does better for YOUR property