The big changes to v1.3.1 quick battles are:
5 potions down to 3, ribbons based on planeswalker levels, 300 runes for all quick battle wins (with new unknown rune sinks).
Initially I thought leveling all Planeswalkers to 50 would be most efficient, but as I thought more I came up with a different strategy:
Some Planestalkers get arguably weaker at higher levels, due to abilities costing either significantly more and/or having undesired effects (Lillian’s 2nd ability at level 3) (Gideon’s 1st ability at level 3), (Chandra’s 2nd ability at level 3), (Jace’s 2nd ability at level 3).
Here are my thoughts:
Nissa: [Level Recommended: 50]
Her abilities only get stronger as she levels, she is the best candidate to level to 50. She has powerful creatures and great mana gain creating potentially fast games at even high levels of HP.
Chandra: [Recommended Level: 30 or 40]
Her greatest ability (2nd ability) (imo) is weakened by a 50% greater cost and an often unused utility at level 44. Her mana gains after level 30 are marginal, and shes all about fast burn games so leaving her at 30 will give her a more efficient first ability and lower enemy HP pools at the expense of 1 ribbon per game. Alternatevely, level 40 she might be a bit better or worse, it increases ribbons by 33% per win from lv 30, but is only worth it if games take less than 33% additional less time.
Lilliana: [Recommended Level 30 or 37]
At level 38 her discard card spell becomes much less efficient, so many argue she is not worth leveling past 37. Normally I would suggest to stay at 30, however at level 34 and 37 she gains additional mana bonuses. Both level 30 and 37 will award 3 ribbons per win, however level 37 will have a much higher mana gain at the expense of higher planeswalker HP levels.
Jace: [Recommended Level 40 or 50]
At level 44 Jace’s second ability at level 3 costs 33% more and often provides little to no benefit to some of his major spells that cost 7 or less (Talent of the Telepath, Aether, Days Undoing), additionally he only gains 1 extra mana bonus from lv 40 to 50, so it could be argued that it’s more efficient to keep him at level 40 with lower HP pools and a better 2nd ability. Alternatevely level 50 could work as well as his 2nd ability isn’t used as often as his first and the extra ribbon might be more time efficient.
Gideon: [Recommended Level 2, 8, 33, 50]
Because of the 3 potion limit, it will be efficient to switch between planeswalkers while other decks regen HP. Having Gideon at level 2 or 8 provides 2 benefits: First he would have little to no HP loss per game, which could be used when low on potions and higher Planeswalkers are low on HP (to prevent downtime), second it would be the most efficient way to gain 300 runes per game (delicious 
's), which may be highly desirable depending on what the new rune spenders are. (Jace at level 3 could accomplish a similiar role). Gideon’s most used ability gets significantly worse at lv 38, because of this level 33 (which provides an extra mana bonus) is a good place to consider. Alternatevely because of his powerful cards, leveling to 50 could also be effective as well.
I think the most important things to consider with all Planeswalkers is don’t level in between multiples of 10 unless there are mana bonuses or more powerful abilities, otherwise you gain no additional power or ribbons, but deal with longer games becsuse of higher HP pools.
Having diverse level ranges will serve to give you a better idea of what is more efficient in quick battle, while also providing a more diverse group of decks to play.(diversity=more fun?).
Remember, you can always level your Planeswalker, but you cannot remove levels, it might be worth trying a lower level first before deciding to go straight to level 50.
These are just my ideas, having all level 50 Planeswalkers may be more efficient.
I hope these suggestions don’t empower my event competition enough to bump me from first place! 
