Hi,
Been through exactly the same process. Went from Pastel Partner to Accpac.
The key is to have a good VAR/Consultant who will make sure the implementation and migration run smoothly.
The ERP software would depend on the nature of your business, some do manufacturing very well, others do warehouse well etc.
Also not sure if SaaS is something that you would look at in either, if so your software choice would need to take that into account as well.
We narrowed down to 3, Accpac, SAP Business One, Microsoft Navision.
If your business is simple and doesnt require ERP customisation and SaaS is an option look at myERP.com