It's my opinion that you'll generally get the better GPA wherever you feel most comfortable.
It's also my opinion that any differences between how easy it is to get a high GPA from one university to the next are minor if they exist at all. In addition, very little to nothing of what you hear on the subject is based on any real evidence.
With regards to how easy will it be to keep up your marks - it's basically impossible to predict what your first year marks will be at any school based on high school. On average people go down something like 10-15%, but some go up, some stay the same, and some may go down 30%+.
