OpenCart Specialist is serious and experienced company that provide all kind of opencart related services like creation and maintenance of your store, improving SEO, upgrade to latest opencart, and much more. You can get more info on official page -

Data Cruncher is a partnered solution where you can import all data from different sources to a Data Cruncher where you can manipulate your data without limit and import it to your store. You can get more info on official page -

iSenseLabs is other serious team developing extensions for opencart, make sure to check their website if you need for extensions that we don't have here  -