You would have to look at it like this......I was trying to make the same decision and these are my thoughts....
Raging Bull vs Nitro, ones a hypertwister, ones an L out-n-back with helix. Both give great rides. Which type would you like to ride? Other than that, even.
Chiller vs V2. V2 gives great vertical effects, while the top hat on chiller is quite a unique thrill. Chiller seems like it would pack a little more of a punch with its layout. Maybe half a point to Chiller.
Batman, same ride, both parks.
GASM vs Shockwave, basically the same.
For wood, Great American wins hands down. Racing effects and size of American Eagle are better. Great American has viper. 2 points for GrAm.
Whizzer, unique ride, while GrAdv has a mine train and indoor coaster. 1 point to GrAm for the Schwarzkopf classic since its one of a kind.
Viper is a togo. Enough said. Not a fan of stand ups here, so Iron wolf evens it out.
Deja Vu, will it be running when you go? Again, with all the problems Vekoma has, i wouldn't count on getting to ride this. 1 HUGE point here to GrAv for their floorless. Another B and M great ride.
Flat rides, Great Adventure wins, they both have looping starships, enterprise, pirate, wave swinger favorites.
GrAm has swingout (does GrAv have this ride?), Condor, Trioka.
GrAv has jump, frisbee, and the Evolution (which is one of the most outstanding flat rides i have seen). Evolution is one of the bigger reasons i want to go to Gr Av.
For coasters, lineup is a little better (especially if you are a wood fan) at GrAM athough they have WAY too many inverts. Flat rides, GrAv has some newer innovative rides. Theming is better at GrAm.
HOWEVER, GrAm is now instituting a PAY fast pass system (see other post). This is a bigger reason NOT to go, to protest this kind of nonsense before it becomes an industry standard.