please read my analysis

my original assumption:

房产	买入价	银行贷款额	实际投资额	第0年Bal	年开支	年收入	净收入	第1年Bal	inflow/outflow	回报率
甲房	50000.00	0.00	50000.00	-50000	2500.00	5000.00	2500.00	2500	5.00%	5.00%
乙房	50000.00	0.00	50000.00	-50000	2500.00	0.00	-2500.00	-2500	-5.00%	-5.00%
丙房	50000.00	100000.00	-50000.00	50000	2500.00	5000.00	2500.00	2500	205.00%	-5.00%
丁房	50000.00	100000.00	-50000.00	50000	2500.00	0.00	-2500.00	-2500	195.00%	5.00%

it may be difficult to judge which one is better between A甲房 and D丁房

let me assume:

房产	买入价	银行贷款额	实际投资额	第0年Bal	年开支	年收入	净收入	第1年Bal	inflow/outflow	回报率
甲房	50000.00	0.00	50000.00	-50000	2500.00	10000.00	7500.00	7500.00	15.00%	15.00%
乙房	50000.00	0.00	50000.00	-50000	2500.00	0.00	-2500.00	-2500.00	-5.00%	-5.00%
丙房	50000.00	100000.00	-50000.00	50000	2500.00	5000.00	2500.00	2500.00	205.00%	-5.00%
丁房	50000.00	100000.00	-50000.00	50000	7500.00	0.00	-7500.00	-7500.00	185.00%	15.00%

here, according to your ratio, D is much much better than A: 185% vs 15%, and ROI give the same: 15%.

but basic instinct: A: you can earn $7500 on 50k investment, cannot complain.

while for D: you have to lose $7500 each year with 50k cash out at the begining, it's equvalent to borrow a loan of 50k with 15% interest rate, very bad!

I hope this makes my point clearer.