When an aggregator is the right answer
When your reviews are already somewhere else and your store shows none of them. A shop that also sells on Etsy or Amazon, a business with a strong Google profile, a brand whose customers talk about it on Facebook — in each case the reputation exists and the storefront is the only place that does not know.
It is also the answer when you want one consistent widget rather than two that look nothing alike. Running a product-review app and a Google widget side by side on the same page is common and it always looks like two products bolted together.
When it is not
If you need review request emails going out after fulfilment, per-product star ratings on collection pages, photo uploads from buyers, or review syndication into Google Shopping, pick one of the product-review apps above. Those are real needs and we do not serve them.
A reasonable setup for a growing store is both: a product-review app for per-product reviews, and an aggregator for everything earned outside the store. They do not conflict.
How we would choose
Small store, tight budget, wants product reviews: Judge.me. Product photos are central to the brand: Loox. Large catalogue with real requirements: Okendo. Reviews already spread across Google and marketplaces: ours, and the free plan is enough to find out without paying.