Niches and Keyword selection strategy - what do you use?

I'm trying to put in place a system which selects Longtails which will be easier to rank for. Of course, the system is automated and scrapes data from Google Search and Google Keyword tool... but I'm not sure what factor should get more importance. I dont want to ever look thru the Keyword list manually... so there should be a reliable underlying selection criteria.

There are 4 kinds of Keyword parameters that I'm scraping and want to use...

1. Hits, without quotes
2. Hits, with quotes
3. Intitle, with quotes
4. Monthly Search volume

But some Longtails have a huge difference between normal and quoted Hits. For ex.

online mortgage brokers 13 mil hits
"online mortgage brokers" 30K hits
intitle:"online mortgage brokers" 76 hits only
Monthly Search Volume 540


From the above, we see that the last 3 factors clearly say the Keyphrase is a usable Longtail. But the Hits for unquoted search are over 13 million. So, should we ignore the unquoted-search factor altogether?

What factors do you guys use in selecting Longtails and do you use some kind of Weighting formula for the parameters involved?

You brought up a good point... that since people always search unquoted (including me) so my actual phrase will get pushed down. I was considering dropping broad match parameter altogether, but your reasoning has convinced me to retain it. :biggthump

I have a decently good number of Blogs and Profiles in operation (~400K at present) and have been able to rank for new Longtails in as little as 15 days on pure autodrive (custom coded system)

I just need to focus the Longtails, since right now they are being randomly selected from a large pool (~130K) of scraped Keywords and so my backlinking power is being frittered away on unwanted keywords.

Yeah I realised that "Naruto episode" will get a lot of broad keyword results. but this is because of people typing in "naruto episode 1", "naruto episode 86".

I decided on the criteria as below...

Unquoted Hits should be less than 3 mill
Unquoted INTITLE Hits should be less than 50K
Monthly SearchVolume should be more than 300 actual volume (Not Adwords data)