Either one will team well with a Balance wizard. It really depends on what roles you and your friend want. If you chose Storm, your friend will mostly need to be support and healer while you mostly attack. If you choose Life, you both can alternate between hitter and support/healer depending on the circumstances.
I think you should go with storm if you will be playing with a balance. I have a storm and balance combo that I quest together and they sail through content with balance playing as support for storm and with storm quickly defeating the enemy. Obviously any school can play any role in battle if you really want them to, but balance and life much more easily adapt to a support position and storm is known for its ability to hit fast and hard.
If you're running with a Balance and wish to make it easy, choose Storm.
If you would like to make your gameplay with them more challenging, choose Life.
Best of luck! S.S.
Shannon has got it spot on.
I generally like to play as more than , but that's just because I like to play support more than attacker.
I would probably recommend that you do in this case though if you want to progress quickly later on. You can always train in as your secondary. (You can do the reverse too, but it's not as recommended).
Good luck on your adventures to you and your friend!
I prefer Storm. Balance is already pretty support-ish, so you don't really need a Life to heal them when they have their shields and Weakness. Storm on the other hand dishes out some really good damage throughout the board and can help you guys progress faster.
Also a little tip if you go Storm. Once you get around 500-900 gold in the early game and get Storm Shark, buy as many Keen Eyes TCs from the bazaar at least once a day. Then go to Golem Tower with nothing but Storm Sharks and the Keen eye cards in your deck and make around 30-50 Storm Shark TCs with 85% accuracy so you don't fizzle as much and can successfully pump out more damage.
It doesn't make that much of a difference, however in my opinion, I believe that you should go with storm. If balance wizards are good at one thing, it would be being excellent support wizards with a barrage of blades and shields to use. Storm wizards can benefit off of them and be the main attacker wizard in battles. That's only my input, but I think it's a good strategy for your sake.
, but that's just because I like to play support more than attacker. 
