I'm not sure I've ever thought of Georgette Heyer as having any "Greatest Hits", but according to Sourcebooks, who publish her in the US, she does. Because an omnibus of her "Greatest Hits" is now on sale for $4.99 at Kindle and Kobo US (coupon/VIPable). The three titles included are
Arabella,
Frederica, and
The Grand Sophy.
My absolute favorite Heyer title is
The Unknown Ajax, but
The Grand Sophy is probably my second favorite, although
Devil's Cub and
These Old Shades are in the running for second place too.
Arabella and
Frederica are up there on my Heyer list also, though, so this is not a bad stab at a "Greatest Hits".
I haven't seen/noticed the Sourcebooks/Heyer Birthday sale for a few years (???), so if you need and want these, this is a pretty good price. Especially since Sourcebooks normally prices Heyer titles at US $8 and up - mostly up

.
Kindle US:
https://www.amazon.com/dp/B082VN5J22
Kobo US:
https://www.kobo.com/us/en/ebook/geo...-greatest-hits