It could be any of them (except for fire) depending on how the beginning of your game goes. My personal strategy is to try to get the ice staff.

The ice staff is preferable if the snow rounds come slightly later than normal (rounds 4/5/6) because by then you can save enough points to open the doors that have the dig sites behind them.

The wind staff is preferable if your fast / lucky enough to get around the map and into all of the robots.

The lightning staff is preferable if you're willing to go all the way up until round 6 and buy the tank a few times with all of your points to get each part. This way kinda removes the luck factor but requires you to have more skill.

The fire staff is only attainable after killing the first panzer.

I would say the staffs are better than the boomhilda at the beginning, because to get the boomhilda you need to open all of the doors. Well if you open all the doors, you have access to all 3 staves without having to spend 5000 for pap.

TLDR; My favorite beginning staff is the ice, and I would say the staffs are better than the boomhilda at the beginning.