That is a hard question to answer.. Nothing is best for everyone... However if i am to generalize it I would put it this way.. If you want to cut everything from a short promos to hollywood pictures..
A high end windows pc (only cause mac pro hasn't been updated in ages)
Avid Media Composer with Nitrus DX
Two monitors
Broadcast monitor
HD Deck
pimping 5.1 speakers
A good mixer
You are looking at over 70,000 or 80,000, could even approach even more.. HD decks run atleast 15k.
If price is not an issue then there you go....
However this is not realistic for most people nor best solution by no means... I run a macbook pro with Avid (as primary) Final Cut 7, Final Cut X (for practice, didn't have to use it for a job yet), and Premiere (just in case)
I am a final cut child who grew up on it and love it however everything I am doing in last few years is on AVID...
Have a second monitor..
I am very portable and rest of the gear I usually get where ever I work at.. I am looking into getting a good broadcast monitor connected with AJA thunderbolt..
Like I said this is very open question, there is no (BEST) it all depends what you will be doing.. If you get AVID (which can do everything, however is cluncky as **** and counter intuitive) but you are only cutting wedding videos and short format stuff, it would be an overkill galore.. Just get FCP X in that case... Simple,easy, one app...
Be more specific and you will get clearer answers..