Generally, my go to combo: for a prespray, I use a 2 gallon pump sprayer with the following mixture: Chemspec traffic lane cleaner and Matrix enzyme pre-spray. Water should be between 140 to 170 degrees. Agitate the bad areas with a brush and let sit for 5 mins. Extractor rinse with Matrix all fiber rinse. In a pinch, I will replace the Chemspec tlc with Zep carpet cleaner from home depot. Otherwise, I get all my stuff from a local Jon Don.
For machines, I'm using my Mytee Spyder or EZ Spot portable for away jobs. And my Century 400 Ninja when working out of my own garage.
Just a suggestion . . . there's no set rules as to what's the best product. Try a few different combinations and see what cleans the best and is most cost efficient for you. Autopia is a fantastic place to get recommendations from people with experience. I think it was mentioned earlier, Grouse is a good guy to check with too.