I have been researching on getting dive certified. So far in my area I know of PADI, and SDI/TDI. . . . I'm looking for a school that is going to take the time teach me the fundamental basics without rushing me out the door to start diving.
I do not believe that the answer to your ultimate question - where to pursue dive training - is as much a function of agency (PADI, NAUI, SDI/TDI, SEI, SSI, etc., etc.) as it is the particular shop or facility, and the instructor(s) involved. At the Open Water Diver level, there are enough curricular commonalities across training agencies that the dissimilarities are of marginal importance. However, a good instructor can transform a good curriculum into a superb learning / training experience, while a bad instructor - and, unfortunately, there are a few out there - can turn a good curriculum into a dog's breakfast. So, I have three suggestions:
1. Ideally, you will receive location-specific feedback to your post, based on where you live, that will give you some possible sources of training. Heed those personal experiences.
2. Visit several dive shops in your area, perhaps shops with different agency affiliations (e.g. a PADI shop, a NAUI shop, a SDI/TDI shop, etc), and get a first hand 'feel' for the style of those particular shops. You may not find THE one and only one place you want to train, but you may very well find several places that you DO NOT want to train.
3. Irrespective of what you hear by way of feedback about a shop, or an instructor, find out who the instructor for a course will be and interview that individual. If a shop cannot accommodate such a request ('Uh, we're not sure who will be teaching the class, yet', or 'The instructor is too busy right now, just come to the Orientation session for the course and you can meet them there'), you have found out that the facility is NOT where you want to train. There are several threads here on SB that address some of the things you should look for in an instructor / class. One that I think is particularly useful was posted about 5 years ago:
http://www.scubaboard.com/forums/ne...ng/287780-how-find-excellent-scuba-class.html.
There are many good shops, and many good instructors, out there, affiliated with a variety of good agencies. But, you want to find an instructor that matches well with your goals, and not every instructor may be a good fit, for YOU. (And, by the way, if you talk to personnel at a particular shop, or to a particular instructor, and they spend most of the time telling you how bad other shops, other agencies, or other instructors are - rather than sharing with you what they have to offer - you probably don't want to train with them, either.)