Both are as bad as each other and have been implicated in many war crimes and human rights abuses, however Israel has more firepower and can inflict much more damage (E.g. demolish an entire apartment block, killing hundreds of innocent people from the air).
The last thing any country should consider doing is arming or funding either side, that will be like throwing fuel on a fire. Taking sides in what is essentially a regional ethnic conflict between extremists on both sides is not a good idea.
Again, not condoning or justifying the actions of either side or taking any sides here - they are both as bad as each other.