PRP hair loss: Is it better to see a dermatologist or plastic surgeon for this procedure?

Any cosmetic Doctor, dermatologist or plastic surgeon trained in PRP injections for hat loss can perform the service. I would suggest you not have the provider add acel. My experience has been that it doesn’t help and might actually retard hair growth. 

I recommend seeing a board-certified doctor with experience using PRP for hair growth. Prp is effective, but I have a very specific protocol, every 3-4 weeks for 6 months with prp therapy. I also add in progesterone to speed the healing process.  After that the injections are tailored down. You should also be on viviscal and other growth promoting ingredients. See an expert for a formal evaluation. Best, Dr. Emer

Just because "any" doctor can perform PRP doesn't mean that they should. Most PRP Hair Growth providers today, sadly, are not ABHRS (American Board of Hair Restoration Surgery) certified and have little experience in diagnosing and treating hair loss, have never taken a single certification course specifically for the Medical Management of Hair Loss, don't know how to determine if you are a good candidate for PRP, and unfortunately even far fewer are measuring or tracking hair growth or hair loss scientifically.
Many hair loss patients come to Bauman Medical after having a 'failed' or exceptionally painful PRP elsewhere and they are looking for a more sophisticated and stronger PRP treatment that is virtually painless. 
The use of ECM extracellular matrix like ACell or BioD in our practice in thousands of treatments since 2008 has been shown to prolong and strengthen the effects of the proper application of PRP (we presented this data in ISHRS Bahamas in 2012).  PRP+ECM can provide 10-20 months of "boost" to the treated area before a repeat treatment is needed. Science shows that without the addition of ECM you are likely to need a treatment nearly every month to maintain improvements and once you stop the treatment for more than a month or two, your hair will return to what it once was. Yes, PRP+ECM is typically more expensive, but you will need less treatments over the year and see a stronger response from it.
Non-chemical, all natural ECMs like ACell (porcine bladder) and BioD (human placenta-derived) are for tissue regeneration and repair and have been used safely in 100,000's of procedures in orthopedics, ophthalmology, general surgery, dermatology, cosmetic surgery and many more specialties to help people heal faster from wounds while decreasing the production of scars. While every case is different and there is always some risk with any procedure, we have NEVER, EVER seen a side effect from the use of micronized ACell or BioD in thousands of PRP treatments since 2008. 
The fastest and least invasive method of measuring hair growth in the clinic is with the HairCheck device. This scientific cross-sectional bundle measurement allows us to accurately measure several areas in EXACTLY the same spot over time without a tattoo or shave. It has been shown that patients with the greatest success with treatment have HairCheck measurements 2-4x per year.
Seek out an expert who is experienced in PRP and other forms of hair restoration to help you determine if you are a candidate and what areas you would expect to see improvement. Be prepared to get a second opinion, "virtually" if you need to via skype/facetime, before you waste valuable time and resources.  
Sincerely, 
Alan J Bauman, MD, ABHRS - Medical Director - Bauman Medical