1. ZERG
Lets start of with Zerg. There are a lot of stategies/build for zerg but I think this is the most dominant and common:
WOL - Late game, hard to reach, Broodlord Infestor
HOTS - Hard to control, Mutaling-Bling/Roach-Hydra
LOTV - Hard to reach, Roach-Ravager/Ultralisk-based builds
2. PROTOSS
For Protoss, if you'll notice, the core has always been warpgate units:
WOL - Micro-intensive 4-Gate
HOTS - Sharp-timing, Sentry-Blink stalker
LOTV - On a timer, Adept-based builds
3. TERRAN
And ofcourse, Terran, the most sophisticated race. You can see how their strategy is very diverse and has evolved throughout the years. You need to be super intelligent to change their strats for every expansion:
WOL - MMM
HOTS - MMM
LOTV - MMM