What the apps in this category actually do, which of them solve the problem you have, and where Store Huddle is the wrong answer.
Shopify lists 114 apps under Staff notifications. That sounds like one crowded market and it is not. It is three, and merchants lose time because the category name hides the difference.
Shift and payroll tools answer who is working and what they are owed. Time clocks, rotas, commissions, PTO. Alert relays forward a store event into Slack, Telegram, WhatsApp, email or SMS, and stop there. In-admin work tools are where the work is done after the alert. Most of the category is in the first two groups.
Each page below says what the app is built around, where the two genuinely overlap, and which one to pick. Several end by recommending both, because a time clock and a coordination workspace are not competing purchases. No prices: they change, and a stale one makes a page untrustworthy about everything else.
For general tools rather than Shopify apps, see alternatives.
The most installed app in the category, and for most stores the answer is not either-or.
The closest messaging overlap in the category, which makes the difference worth stating precisely.