Pro Tools is a professional standard, yes, but Pro Tools LE kinda pales in comparison to Cubase SX (flagship version.)
Things PT LE doesn't have that SX does;
- Timecode included
- Surround mixing
- More than 32 audio tracks
- More than 8 stereo busses
- I believe Cubase also has more than 5 inserts and sends.
- Freeze track
- Automatic plugin delay compensation
- OMF import and export
- Cubase has a WAY more flexible mixer and view settings
And those are just off the top of my head.
Pro Tools *is* a standard, though, so it had become a default digital format for interchange between studios. If you don't need that, you may be better off with Cubase.
On the plus side of Pro Tools:
- fewer windows to get everything done, a bit more intuitive
- Rock solid integrationn with your audio interface
- Wicked editting capability: easy, fast, and dangerous
- IMHO a marginally better assortment of meat-n-potatoes plugs (
EQ III, BF76, and some other fun stuff if get a 002r factory bundle. Neither of them comes with a particularly impressive Verb

)
- PT comes with Reason Adapted, which is a better drum machine and synth than the plugs included with Cubase, IMO.
Keep in mind that Pro Tools is LOCKED to its hardware. If you buy an Mbox and need more than 2 i/o, you have to shell out for the 002r or 002. There is no adding to a PR LE system, you just replace it with the next step up. Digi does have trade in offers, to their credit.
All that said, I love Pro Tools. I just don't have any illusions that its better than the competition. It isn't.
Take care,
Chris