Hi Bob,
As one who spent several years in the hazardous waste business I have to say that I don't beleive there is a best. There are many very good products out there. Respirator fit is most important and they don't always fit everybody the same. Go try several kinds and buy the one that fits you the best and is most comfortable for you to wear. If it's not comfortable you won't want to wear it. As far as protection goes a full face respirator is best. The protection factor for a full face vice a half mask is 50 vice 10. I personally have two different full face masks and a half mask. I prefer the Wilson brand but there's so many different kinds. I didn't look at the site you suggested but I'm sure they tell you what to do to check fit. The best way (Quantitative fit test) is a high tech computer test required by OSHA every six months but for the average hobby guy just go through the easy check of blocking the inhalation port (the filter) and suck in if it leaks it doesn't fit or is damaged. Then check the exhalation port by blowing out. It should lift off you face a little but no air should escape through the mask itself. All that said pay the bucks, wear it and take care of it. Hope this helps!