Depends on team size.
I am testing a lot of tools for months since I am agency providing multi channel at a significant scale.
There is no solid tool for scaling many emails and many linkedin accounts if you're managing multiple clients since LaGrowthMachine would be costly.
Here are some of the better multi channel tools:
overloop .com (not aI one)
Although if you are an agency and want to do many LI accounts with InMails, 100s of email inboxes then automating connection between Smartlead and Hey Reach might be best for now