All depends on the car. It is just like any other business, most steak houses have some seafood on the menu, but it isn't why people go there. B-J is good for over-the-top restos that have tons of eyeball. IMHO, the B-J buyers don't seem too concerned with buying a car that is really correct or what I would call a thoroughbred car. In other words, a really flashy, well done, regional-type show winning car may break the bank at B-J. With 100% no reserve, you have to make sure you send a car you are positive will find a buyer. I've done really well on cars at B-J, and I've also taken a few really bad hits. After 12 years of consigning cars there I like to think I know what will work (even though last year I did well on 2 and just average "no-brainer" money on 2).
High-end european stuff I have always sent to RM, and in fact have my 65 Shebly GT-350 R Model consigned there for this January. Some cars need a catalog description to tell the whole story, and it is a different group of buyers at RM. They know what they want, as in the exact car, and prefer the more civilized enviroment of a catalog sale. As a consignor, I like the fact that I can have a reserve in case the right buyer gets the flu and doesn't fly in to buy my car
But out of all the auction companies, the one I use the most as both a buyer and a seller is Mecum. Dana Mecum has treated me like a king since the first sale of his I went to many, many years ago. They are honest and really work hard for both sellers and buyers. If you've been there, you know. There is no "shot clock" on the podium, the car is there until a deal gets done. And Dana works nearly every deal to make everybody happy, even if it means cutting his already cheap (5%) fees to get it done. I think the amount of people that rave about Mecum is a fair indication that he has built a "car guy" auction company. Anybody that throws stones hasn't done business there. Mecum has loyal buyers and sellers. Yes, I take a few cars a year to B-J, just to be a part of it and roll the dice a little. But I have had many positive experiences at Mecum and have sold a lot of high priced stuff that I always felt was handled professionally and what I call "win-win" deals for all involved. If you look at sales like the Randy William's collection, or my #18 ZL-1 last year, you can see they get the job done.
All of this are just my observations. As a guy that uses all of the auction companies, there isn't one that I would tell anybody to avoid. In the end, it comes down to who has the right venue for your car, who has a sale that is convenient for you to get your car there, and who treats you right and gives you the best feeling that they will give your sale the attention it deserves. Year after year, I use Mecum for the majority, a handful at B-J, and a few at RM.
Hope this helps.
Colin