Daiquiri is my usual go to, but Summer always throws me into drinks with ice. Mojitos will be followed by the Mai Tai, and then I'll find my copy of Smuggler's Cove and get my drinks mixer plugged in. How is the Rum selection in the Southern Hemisphere?
Minty soda water is also a good way to stretch out the remaining ice in Summer...it's a precious commodity unless you have a massive freezer somewhere (or even a smaller freezer NOT stuffed with your frozen excess harvest of Summer strawberries...).
The Mojito always struck me as intentionally lazy. It's hot. You're tired. Do you REALLY want to be shaking, straining, cleaning up, trying to find the compost bin at the back of the kitchen? Am I working in a bar being paid for this while the AC keeps me chilled to room temp?
Hell no! It's 25C+ outside! I want to chuck stuff in a glass, stir, and probably reuse the mint for the next one. Just to avoid the 20 steps to the herb garden when I have two pots of prolific mint to snatch a few shoots from... I second another commenter on making a soda water cooler in between Mojitos. It's criminal to waste ice on days like today!
If you want to boil it down, the dilution is the main difference I think. A Daiquiri is shaken in ice and served up (dilution ceases after serving) as a Sour. A Mojito is stirred in crushed or cubed ice and the ice stays in the glass with an extra dash of soda water so its a larger volume Collins type cocktail.
It being mid-Summer, I think we'd appreciate the Mojito over the Daiquiri as it stays colder for longer and has more chilled liquid to down.