I've dealt with Danny at SMC and Tom at SPC many times. Can't go wrong with either. I buy all my packs from SPC nowadays. No real reason I picked one over the other. Basically for me, Tom has helped me out in depth many, many times. Not just with batteries, but also charger selection (he doesn't sell chargers either), and what power supply would be best for my needs, heck he's actually shared vehicle setup tips with me back when I was more into racing.

How many vendors do you know of that go that far above and beyond just selling a product?