I got lucky early on in that one of the first pins I bought was from a guy who did some testing for Art/Comet. He spoke highly of the bulbs, so I gave them a try the first time I used LEDs and was very pleased. Went to York and Allentown and saw what Cointaker and the others had to offer, and didn't see any real difference between theirs and Comet's, other than Cointaker had a much larger, but more confusing, array of choices that were much more expensive. Cointaker does sells some LEDs in sizes that Art doesn't sell yet, but as Comet continues to roll along I don't think that will always be the case.
I will also say, that the second time I ordered from Art, I screwed up on-line and placed the order twice, unbeknownst to me. Art recognized this as a possible error, called my house and talked to me, corrected the order and refunded my credit card. After that, I knew I wouldn't be ordering from anyone else.
And finally, Art also sends candy in your shipping box! If a few free Jelly Bellies don't bring a smile to your face, you're inner child has left the premises!!!