total for damage, defense, mobility
risk/reward is supposed to be balanced, yet there are champions that have cc, tankiness, and huge damage (think wukong). There ought to be a balance between the parts. And no champion should have more everything. If a scaling factor for damage vs defense could be made, and adjusted for things like cc. Then the total ought to be the same for all champions, and adding attack should diminish health/defense. Putting in cc should drop both. But ultimately, all the elements should add to a specific number when looking at the total. Wukong could not have so much defense and still be able to attack at high damage rates, especially with his knock-up ult (with a 400% ad added in). Syndra might be able to do a 2000 ap damage, but then she would also be so vulnerable that a support could kill her with little effort (think 4 basic attacks from a low to medium powered champion). If a Syndra doesn't want to die easy, then build more sustain (which would by force drop her power). Maybe the total ought to be about 2500 ... or maybe 3000. You could then have 2900 attack but then only have 100 health. Or 2900 health and then only 100 attack. Put in a " speed"
That would be total balance, and would make the strategic decisions (how to build) much more challenging. Different champions would then start with some basic balance, and items could reward play with allowing additional crafting of the overall numbers, but the numbers should only grow very marginally (if 3000 is the base for all champions, 3500 ought to be close to the top end).
Say goodbye to a champion that can come in, destroy you and get away without any chance of your being able to kill them (regardless of what champion they are or what champion you are). Strategy becomes much more important if champions don't really work well if they can insta-kill any other champion. It would actually take thought beyond "who is weakest, and how can I move tactically to be able to get in, kill, get out?" It would take much more than just tactics and every 1v1 battle would not be one sided. Way more fun ... less like a FPS.