Last month a Repeat Customer Insights customer was asking about who their top 40 active customers were based on total spend.
Both of those segments can be found in the RFM analysis. Active would use the Recency portion and spending would use the Monetary.
These customers would be highlighted by a high Recency and high Monetary score. I'd recommend the 4th and 5th scores in each and maybe the 3rd depending on how large of a segment you need. The more scores you include, the larger the segment size.
You can also use the Recency-Monetary Grid and the two segments that are close to those scores: Recent high spender (RM) and Recent whale (RM). That'll include more people but they'll have similar behavior.
Repeat Customer Insights comes with a 14-day free trial so you can see what these segments would look like in your own Shopify store.