As you haven't said what you really wish to use the computer for, it is rather difficult to advise you in detail.
As the others have stated, both computers are excellent. I have had a MBP and currently have a MBA; both were excellent computers but they answered different needs at different times.
Essentially, if you want power (and are into video, graphics, gaming etc), go for the MBP. Equally, if you want a machine that has better specs, more power, and is better value for money, again, the MBP should be your choice.
For sheer portability, the speed of the SSD, and better screen resolution, try the MBA; the current models have just been upgraded and feedback so far has been pretty positive.
Re your "dilemma" - to my mind, the answer might be: If you want a computer, maybe wait for a while and see what the updates to the MBP line bring. If, however, you need one, buy it now an enjoy it.
Good luck with it.
Cheers