Ask yourself one question - do I want to fly
commercial pax/frt around the globe for the next
thirty plus years or do I want to enjoy some
rather more demanding flying for a finite period
of time and then explore the somewhat more
mundane world of commercial aviation ?
The military route will see the indoctrination
and bull**** phase followed by high quality
training and hopefully operational flying. Remember however that not everybody gets to fly
fast jet aircraft - many will fly helos, tankers,
transports, AWAC's and the like which you may
not find quite so inspiring - don't underestimate
these roles however - they need a lot of balls too.
The civil route will be more mundane but eventually pay better assuming that you follow
a path to the majors on large commercial jets.
Of course you may decide to fly floatplanes in
Alaska or Canada, fight fires, operate casevac,
or any other of a host of 'different' types of
commercial operation.
At 18, the future looks like a long path ahead -
you have time to have a career in both the
military and civil fields if you wish - at the
end of the day what does your heart want most -
there is the answer to your qusetion !