Two of your key deciding factors should be:

1) Will they hire me after I get my ratings? (note: some schools "hire" all CFI graduates, but you will sit around with 38 other CFI's and fly once a month). Actually this may not be as important today as in the past, I think there is a CFI shortage due to regional hiring.

2) Where will I get my multi-engine time? 100 hours is good enough in todays market, but that will change, so assume you will need 300 to be competetive for a regional job. Many schools have little or no MEI opportunities. You might be able to freelance MEI on the side at the FBO, but you will need 100 ME hours to teach twins at most clubs. A CFI with 2000 single engine hours has about the same airline employment opportunities as a 60 hour private pilot (none whatsoever).