I think German universities accept both A-levels and IB. I think it's a common consensus that IB is harder than A-levels. If you want to challenge yourself then IB would be a good choice.
I did IB and I can only speak for IB. I think IB is a good programme, but the experience really depends on the teaching quality and how good the school is. So if your options of schools have good facilities, good IB teachers and high average IB exam scores in the past, I think your IB experience would overall be good.
Also, IB requires a lot of self-management, if you can manage your own time properly and able to work independently, I think you would be fine for IB.