What is the best air filter to use?

Question:I see commercials by different manufacturers all claiming to be the best, so i'm looking for people who have experience with filters and can tell me their opinions on the ones they use. Thanks.

Answers:
The absolute best filter would be a bag-in bag out HEPA filter with a 2" or 4" pleated prefilter. These are very expensive. The electronic filters do a good job but are costly to install. For most applications a good pleated filter changed often is good enough.