based on personal experience Tactics is longer with greater variety of things to do during and after you finish the game, the class system is very indepth and encourages you to use them as enough useage of one earns you new ones where as with Arc, there really isn't much encouragement to mix and match your team, you'll just end up using the same main units over and over again without any encouragement to explore.
A lot of time can be spent trying to figure out the best team combination (assuming you aren't using guides and what not).
Combat in tactics is more fun and more indepth, some elements in Arc can leave you scratching your head (allies missing a 95% hit chance and enemies scoring critical hits from a 5% hit chance) but others can leave you with a greater appreciation of the game (free hits from gemed allies). But with Tactics it's much more fun and less eye brow raising, if you screw up, you know it's your fault 9/10 and not some cheap mechanic.
I know I'm kicking Arc here but if I was judging this game on it's own legs it would be a 9/10 however Tactics wotl is just more superior in every way (except story :D).
That's my own opinion, I know others will disagree.
PS One/2/p/3slim/Vita owner. I survived the Apocalyps3/Collaps3 and all I got was this lousy signature.
Xbox One: What are you doing Dave?
