The decisions/choices you have in 8b is exactly why 8b is easier. Deciding what to take in 8b is not rocket science. It forgives poor position play with a choice of object balls.
The "map" that 9b forces you to take is what makes rotation games more difficult.
The statistics have already proven that breaking and running in 8b is much easier at the pro level;
http://billiards.colostate.edu/threads/break.html#statistics
As far as the easiest games to run out a rack in?
IMHO easiest to hardest: 14.1, 8b, 9b, 10b, banks, 1 hole.
Now easiest to win the match?
That's going to depend on the format i.e. alternating break, length of match, to what score, and rule set.