Which is better treatment for a blood blister?

Well the epsom salts you mentioned can be used to reduce the swelling, but if you want to remove it completely you can sterilize a needle with alcohol or holding it in an open flame until it turns bright red. Clean the area around the blister thorougly, puncture it gently with the needle, and gently squeeze it to drain the blood out, then apply an antibiotic ointment with polymyxin and/or bacitracin in it. Try not to use ointments with neomycin since it can cause an allergic reaction. Wrap it in some gauze and cover it with a bandaid. Be sure to look for signs of infection, like pus, warm or red skin around the blister, swelling, fever, or red streaks leading from the blister.

I thought you were just supposed to leave them alone?

I dont think their is much of a difference. I would use a needle. Thats what my dad does.

Use a clean sterilized needle and pierce the blister at the base next to the normal skin. This should allow the blood to drain.