For me this is the one that started it all! Originally released in 1979, this massive 1/72 scale kit caused a sensation in the ship modelling community. The original Matchbox version contained parts and markings for HMCS Snowberry, HMS Bluebell, or USS Saucy. Revell acquired this kit in the 1990's and since has released several re-boxings with new box art as Snowberry and Saucy. They also released "Platinum" and "Technik" versions which include upgraded metal and working parts and lights respectively.
Measuring 33 inches long competed, this model is very popular in the R/C community and readily lends itself to conversion as a working model. State of the art when released, the kit's fine details are somewhat crude by today's standards however that should not deter anyone because it still builds up into a big, impressive, and pretty accurate model, and those wishing to upgrade will find a bounty of aftermarket parts available. The guns in particular could use some help; the pom pom and 20mm weapons are poor representations of the real thing. You should note this kit represents an "extended forecastle" corvette with the widened open bridge and the pom pom further bandstand forward. Only the first dozen or so Canadian corvettes had the bandstand in this position; it was quickly moved to the end of the engine room casing. You could build a model of Sackville with this kit; it would benefit from a few changes (the bandstand is perhaps the most obvious, also Sackville doesn't have the galley hut in front of the stack). One bigger issue is that the decks have a wood grain, which is completely wrong for any Flower class corvette. It's not too much of a chore to sand that off if it bothers you. While this kit may not be in production at this time, you can often find it on Ebay and in the secondary market. Original retail in 1979 was around $80CAD; today you can expect to pay probably $200CAD on average. If you find one for $150 or less, I'd snap it up. I bought the one pictured here on Ebay; that original box art still grabs me every time!
Released in 2015 in 1/144 scale; this Revell kit is a whole new effort and corrects many of the issues with the Matchbox kit. Measuring around 17 inches complete, this is a more compact model but it benefits from considerable advances in model kit design and production. The details of this model are much finer than the old Matchbox kit; the weapons are all well represented and the decks have lost the inaccurate wood grain. One issue is that the bow of this model appears to match the later "Improved Endurance" version of corvettes with more flare and rake. While not a glaring problem it nonetheless is inaccurate for Snowberry (and Sackville).
Revell released a second version of this kit as HMS Buttercup; that one includes the unusual and interesting "acoustic hammer" designed for minesweeping, as well as a large hawser reel on the stern which I believe was part of her minesweeping fit.
Much like the Matchbox kit, you can build a reasonably accurate Sackville from this kit with a few basic alterations to improve it, and again aftermarket options to pour on the details are plentiful. This kit retails in the $75-$100CAD range when it can be found.
If you are building a model of a Flower Class Corvette, these are probably the best references out there. Canada's Flowers by Thomas Lynch is out of print but can often be found on Ebay and in used book stores. It provides details of all RCN corvettes as well as a wealth of information useful to modelers.
Flower Class Corvettes by Lambert and Brown is focused more broadly on RN and other corvettes, but again provides much useful information for model builders including several colour templates of ships camoflauge. This book is still in print.
Part of the Anatomy of the Ship series, The Flower Class Corvette Agassiz is perhaps the ultimate technical reference and contains numerous detailed diagrams, plans and construction illustrations. Well worth having a copy. I believe this book is also currently in print.