I have various 1/72-scale Sherman kits from Dragon, and was wondering which would be the most appropriate for a 'Normandy Bocage' diorama ... M4A1, M4A2(76)W, or M4A3(76)W ... or perhaps any of these would be suitable.

M4A1 with 75mm gun would be appropriate for US or Commonwealth use. M4A2(76)w was used only by the Soviets. M4A3(76)w didn't appear in the ETO until late in the fall, and only with US troops.
British Commonwealth forces used large numbers of M4A4 (Sherman V) and M4A2 (Sherman III)) with 75 mm guns. Many Sherman VC Fireflies were used, as well.

Many thanks ... that's answered my question perfectly!

I second Gerald's response. In fact he gives a very handy summary of the sometimes confusing Sherman variants in Normandy in one neat paragraph!

As an addendum; in the British zone, east of Caen and the River Orne, where the bulk of Montgomery's armour was concentrated, there was very little, if anything, in the way of Bocage country. Bocage started gradually facing Caen (west of the Orne) and intensified westwards into the US zone. In short, Firefly's (and other British Shermans) would not typically be attacking in Bocage country.

Biggles is correct, though accounts from British and Canadian soldiers do refer to 'bocage country' in the area south and east of Caen,this isn't exactly the same as in the area to the west of Caen and into the cotentin peninsula. The countryside south of Caen is much more hilly with rolling grassy hills, thick woodlands and the typical narrow sunken lanes with tall hedgerows are not quite as prolific.

The US also employed small hatch 75mm M4s and Large hatch 105mm M4s in Normandy. The 105s arrived in July '44, so still in time for Bocage fighting.

The breakout from the heavy bocage country was Operation Cobra on July 25, 1944. The Americans had rec'd M4A1 76W tanks by that time too.

In summary from the above, the US had:
M4 75D, M4A1 75D, M4A1 76W, M4 (105)

Commonwealth and France (fighting in other sectors in Normandy):
M4 75D, M4A1 75D, M4A2 75D, M4A4 75D, Firefly IC, Firefly VC