My first barrel was from Bullberry in 22 k hornet. The workmanship is amazing. Barrel is super solid, it's 10" but it shoots under 1" at 100 yards with factory ammo, on most days anyway. I love the feel of the barrel, it just feels well made.
However, I have read that you have to wait awhile for his barrels. I bought mine because it was in his current inventory and I've always wanted a hornet.
The barrel I just ordered was MGM, it should be in hand in about a week or two. So far their customer support has been really great. I remember with Bullberry, even though the barrel was IN STOCK, I had to wait almost 3 weeks to get it. I called 4 or 5 times and was treated politely, but was never given a straight answer as to what was taking so long. One time I called and they told me they had sold the barrel before I ordered it and I'd have to wait 3-6 months, even though I had already paid for it...after about 15 minutes on the phone that got cleared up, but it still took another week or so to get it.
With MGM, I've called them twice and sent them 3 or so emails and always been gotten back with immediately. They seem to be a higher volume shop(although I could be mistaken).
I don't think you can really go wrong with either. But you may want to call around and see which place has the longest waits. Another person to consider is SSK, I've heard his turn around time and workmanship is great. I'll be able to speak of the quality/workmanship of MGM stuff shortly.
Best of luck!