cart2cart are the most well-known but they're quite impersonal and just provide an online service with no one to talk to.
We've developed software to do migrations and can take care of everything for you so feel free to get in touch: firstname.lastname@example.org
For quick, professional OpenCart support please email email@example.com
The most generated errors being found on Opencart forum originates from contributed programming. The increased post counters are caused by redundancies of the same solutions that were already provided prior.