That is a big question. Here's my personal views on the subject -- they undoubtedly are not widely held.

Airplanes

Pro's:

1) Easier to learn
2) Cheaper
3) Faster
4) More sky to play with (can be safely flown farther away from the pilot)
5) Less annoying to neighbours (noise)
6) Very wide range of flight capabilities

Cons:

1) need much more space
2) need specially prepared facilities

Helicopters

Pro's:

1) Can fly in confined spaces
2) Don't need speciallized facilities
3) Can do amazing tricks in addition to many conventional flight regimes

Cons:

1) Difficult to learn
2) Very expensive
3) Glo-types are very noisy
4) Can't be easily seen & flown at significant distances
5) Somewhat fewer variations in flying activities than fixed-wing types
6) Slow