I've had stuff from both before. I prefer Hattons as they seem more reliable and give a better feedback on what's happening with your order.
On one of my orders from Ontracks I had a train pack and a couple of decoders.
It turned out that the train pack was out of stock but the decoders were in stock.
As I had asked for next day delivery (mainly for the train pack) with insured delivery, I was quite annoyed (spitting nails actually

)when the two decoders arrived the next day and the train pack a week or so later and not even needing a signature on receipt.