Which one is easier and goes at a slower pace?
AP Stat is more work and is a different math than anything you are used to. AP Calc AB is 0 work and studying (basically). However, it can be tricky if you are not naturally inclined at math or do not have a good teacher. It depends what type of student you are. Can you do more work, but easy work? Or would you like little to no work, but study more difficult topics?
Colleges prefer to see AP Calc AB by a mile though, so I would go with AB.
Personally, I think it all depends at your level of math skills. I think AP Stats is easier, but I always struggled in Algebra, which is a necessity for AP Calc. It just depends!
We obviously went to different schools. 
The workload will depend on the teacher. Having said that, for admissions to top schools, Calc is more advantageous.
Which one is easier?
In most high schools and colleges, non-calculus-based statistics (which AP statistics is) is usually seen as an easier course for the less math-inclined (the concepts of statistics are also more useful for those in majors which do not use calculus, although students who do heavier statistical analysis may need to take calculus followed by a calculus-based statistics course). Note that non-calculus-based statistics usually has a prerequisite of algebra 2, while calculus has a prerequisite of trigonometry/precalculus.
Of course, high schools and colleges can vary in this respect.