Best opening?

What is the best opening for white ?

1. f3 2. Kf2. 

It depends on your style... are you an aggressive attacker, or an attacking aggressor?

(AFAIK these is no other style category at beginner's level).

I like d4

the best opening is the grob obviously it's actually the Bird's.

I think it depends on level as well, but I like starting with e4 personally, and the Scotch Game fairly often since it was one of the first openings I learned. 

c4, d4, nf3, and e4 are all great choices, depends on what you specialize in and your playing style though. for more technical and positional players I would say d4 but for agressive players e4, and for hypermodern players nf3 and c4 are great

1.Nc3!!

1.f4!!

d4 or Nf3. There is something to be said for e4 as well. Personally I regard e4 to be tricky. The issue with e4 is that the best players have seen all the tricks and can potentially equalize it quicker, I find it much more likely to get a large edge off of e4.