Who are the best Magento Developers in America is the wrong question, better to ask who are the best Magento developers for our online store and brand.

Best Online Store Option For YOU?
I've used Magento Go and Shopify. I've also used other Content Management Systems when I managed an Ecom team (for 7 years) including home grown and Magento enterprise.

If you want to start an online store which platform should you use? Let's look at a feature by feature comparison:

Easy To Use - Winner Shopify

Plugin / Add On Development - Winner Magento Go 

Email Integration - Tie (both work well with MailChip et al)

SEO - Magento Go if you KNOW SEO, Shopify if you don't

Promotion - Magento Go if you KNOW ecom, Shopify if you don't

Manage SKUs - Tie
up to about 50,000 after than NEITHER (you've outgrown OPP Other People's Platform if you have more than 50,000 unique stock keeping units SKUs). 

Cart - backend Magento Go
(can do more with logic so ASSUMES you know how to create business rule promotions) frontend (what customer sees) Shopify.

Templates - Tie 

Pretzel Logic - Magento Go
(winning this is not a good thing since it means the platform has its own language YOU must learn or things go bump in the night. Magento Go is willing to be confusing and a pain to add POWER, but 95% will never use that power so if you have a small, fun store steer clear). 

Cross Sale / UpSale
Slight nod to Magento Go again assumes you know ECOM well and cross merchandising is not intuitive but is powerful. 

Overall Winner - Shopify
For most readers of this post Shopify is the best choice.

Magento Go honorable mention
for a specialized niche group that needs powerful business rule based promotion, have between 30k to 50k SKUs and don't mind learning a new language to get the backend power they need Magento Go may be for you.

. If you don't know your crosssale (what you do on a product page to move customers to more profitable or popular choices) or upsale (what you do in the car to build Average Order Value (AOV) then use SHOPIFY. 

All you need to know about repricing on Amazon and eBay: how to get started, differences between marketplaces, the "race to the bottom" and repricing tools.

Marty Note
Price arbitrage is TOUGH. If you are an online merchant you need to stay within reaching distance of Amazon or lose more than a sale - you can lose credibility too. You can't beat Amazon, but there are great tools in this post that will help you "price arbitrage" too.

If you are on online merchant, you need to read this post since PRICE is more than PRICE. Price helps create your online brand too. Here are strategies I used to defeat the Amazon price arbitrage monster:

* Created merchandising bundles that were unique to us. 
* Made sure to check Amazon in 3 ways (front door, email and price comparison engines). 
* Hired Scott Wingo's company Channel Advisor to help structure feeds. 
* Gave free gifts with each purchase. 

Hope you can find ways to beat the monster too.  

Sending all traffic to a generic landing page can be a mistake for ecommerce owners. Remember that shoppers who found your store via paid search are different from those who ...

Ecommies - Identifying ecommerce trends, rate and review ecom tools and hold annual awards.

Holiday 2013 Awards
First Ecommies Holiday ratings are in. William-Sonoma & REI.com top the list in November and December.  L. L. Bean gets "most improved" award from November to December and several trends emerge:

* Free Shipping out and back is trending especially in December. 
* Free shipping all orders is trending. 

* Hiding free shipping behind either codes or triggers is declining.

* Deal of the Day is trending with majors like REI.com adding DOD.

* Standard credit card based loyalty programs prevalent. 

* Still many catalog and retail merchandising tactics such as "door busters". 

Ratings report card on Google docs: http://bit.ly/1bPhwz3 

Holiday ecommerce merchandising wasn't very inspired this year. December ratings went DOWN from November. Based on this year's performance ecommerce is clearly in a rut.