What kind of laser is best for removing hair from my neck, as part of my beard? I tried before, but broke out in hives.

The Gentlelase is a consistent, effective and safe laser to treat this issue.  Some patients have a "hivey" type of response after the treatment.  Your body is producing histamines in response to the assault on your follicles. This exaggerated inflammatory response is tough to deal with for the patient, but it's temporary (1-3 days) and the results are worth it. The more inflammation you experience, the more effective the treatment!  Comfort measures can be anti-inflammatory creams, oral anti-inflammatories such as Motrin or Aleve, and application of ice packs 3-4 times for the first day can help make you more comfortable. We have been treating patients for 18 years, and this reaction is rare but manageable.  

In this area I like to use an IPL (intense pulsed light) or BBL (broad based light) which aren't technically lasers. I doubt you had hives which suggests an allergic reaction. It is more likely a just an intense reaction to the laser energy.  It is common to have some discomfort with these treatment and the hives you experienced were probably inflammation of the hair follicles. It is also common to get ingrown hairs with small pustules as the hair that was present works its way out of the skin. You could try having he doctor start with much lower laser settings and work up to a level that works and that you can tolerate. You can also decrease discomfort by using a topical anesthetic before the procedure and a simple over the counter steroid cream after the procedure. 

Breaking out in hives implies an allergic reaction.  You might be allergic to the metal in the laser (nickel is a common allergen)- but this should also show up from wearing nickel containing jewelry.  The other possibility would be an allergy to the products used during or after the procedure.  You should tell your dermatologist about this problem and try to have him/her figure out the cause with you.  Only then, would you look for a different treatment.  I like the Light Sheer Duet laser.  It is virtually painless and does not require gel for the laser to work.