DataD - I thought I understood your original post, but after your reply to JohnT I'm not sure - but I'll throw my two-cents in!
Personally I chose LDR BT/Mono-therapy. After some very exhaustive research into the various treatment options available for my own PCa stats, I narrowed my choice down to either LDR or HDR. I settled with LDR for two primary reasons - one, I found (IMHO) the "Best" at LDR less than 2 hours from my home, (Dr. Brian Moran - Chicago Prostate Center) and two, HDR doesn't quite yet have the track record of LDR. Having said that, again, I believe either would be just as effective - and quite frankly if I lived in the area of the CET/UCLA I may have chosen HDR and Dr. Jeffrey DeManes - who is considered the "Best" at HDR. To echo what JohnT said - find the BEST practioner based on their personal statistics post treatment.
Now the other side of the question - I'm surprised to see your statement about HDR being the most common approach, as when I did my research I found the opposite; here's some of the info I found:
From the Urology Care Foundation: "There are two approaches to brachytherapy for prostate cancer: low-dose rate (LDR) and high-dose rate (HDR). Prostate brachytherapy is most commonly performed using the LDR technique."
From the Department of Urology / University of Nevada: "LDR (Low Dose Rate) Brachytherapy is the most common form of brachytherapy used to treat prostate cancer."
From Wikipedia: "Temporary HDR brachytherapy is a newer approach to treating prostate cancer, but is currently less common than seed implantation. It is predominately used as to provide an extra dose in addition to EBRT (known as ‘”boost” therapy) as it offers an alternative method to deliver a high dose of radiation therapy that conforms to the shape of the tumour within the prostate, while sparing radiation exposure to surrounding tissues."
Obviously there is much more to be found with respect to comparing HDR and LDR, just sharing some of my research.
Hope this helps - best of luck to you.