I did Accounting last year as a 3/4, and I am doing Business Management this year in Year 12.
As subjects, I feel that both are based around rote-learning theory and then being able to apply that to scenarios. Accounting probably has less theory to learn and is 60-70% practical (filling in reports etc), and for this reason I probably found it a bit easier.
However, a conceptually-easy subject in VCE still requires a lot of work. Thus, I would thoroughly recommend that you do Business Management next year, as it will allow you to gain an experience of VCE expectations before you tackle most of your subjects, to focus on your 'harder' subjects that require more understanding-learning in Year 12, and to really focus on one subject in Year 11 (that you will hopefully be able to do well in).
So yeah, I would say go for Business Management