Shopify native tools should be the starting point, honestly. WATI works, but the per agent pricing quietly adds up - two agents is fine, but three or four and it creeps into your budget in ways you didn't price for.
Abandoned cart flows and order updates hit harder when the tool is built around Shopify rather than bolted on after the fact. Less setup friction, fewer background failures that go unnoticed until they hit your ROAS.
I've seen a similar setup from a colleague's product - same principles: shared inbox, broadcast capability, order notifications, abandoned cart recovery, no per agent fees. Not the only option, but relevant given what you're describing.
Whatever you pick, don't lean on demos. Run real support volume through it for a week. Bot to human handoff is where these tools reveal their actual quality - that never comes up in a sales pitch.
What's your rough order volume and team size? Usually changes the answer dramatically.