primarily account, contact, oppty to sales order

if you just have these standard objects, celigo is likely to be your best option because you can use their smartconnector which is pre-built and not super expensive. boomi is more useful if you're doing a lot of custom work (though you can also do it in Celigo, just not quite their bread and butter), or if you plan to have other integrations with other platforms down the road - boomi is truly platform agnostic vs celigo which was originally designed for netsuite and has just expanded from there. I don't know much about mulesoft though, sorry!

Thanks @amy this is super useful!