My 6 week old daughter has severe reflux too. When she was a week old she vomited/spit up, choked on it and had a seizure. She spent 5 days in the NICU. My now 5 year old son had severe reflux too. I tried breastfeeding both of them, but my volume was low and we couldn't get it up enough to make a difference. I noticed the more formula they got the more their symptoms increased.
I would recommend Alimentum (Similac) or Nutramigen (Enfamil). We tried lots of other types of formula with both babies and these were the only ones both of mine could tolerate. It also makes the bowel movements soft and helps with gassiness. Both of my kids showed improvement on the Alimentum vs. soy or regular formula. I think the Alimentum and Nutramigen smell awful, but both of my kids took it with no problem. I think the soy smells awful too. My son drank it with no problem, but it didn't help with his symptoms.
If you don't suspect allergies or if you're just looking for a formula that stays down better, Enfamil AR is also a good choice.
Whichever one you decide to go with, sign up on their website and they will send you checks to use when you purchase the formula.
I know you didn't ask about other aspects of treating reflux, but I thought I'd mention it in case you don't know this...
We have her bed elevated and use a Tucker Sling to help keep her in place. The Tucker Sling was invented by a mom in Kenner

. We got ours from the hospital, but they sell them online too. We also thicken her formula with rice cereal and hold her upright for 25-30 minutes after each feeding. We feed smaller amounts more frequently.
You mentioned 2 meds...I'm assuming Zantac and Reglan? We used these with my son and used them at first with my daughter, but switched to Prevacid about a month ago. It's not as convenient (has to be compounded) but seems to be working well.
Good luck! He should outgrow this in 5-7 months
