Canister vs. White Gas

Ease of lighting

Canister: You just turn on the tap and light, either with a spark lighter, a match, or, on some models, by pressing the button of a built-in Piezo lighter. Voila, instant heat! Piezo lighter convenience encourages you to turn off the stove whenever it's not in use, saving fuel.

White Gas: Lighting requires just a little practice to avoid flaring and takes about a minute. Not as easy to turn off and re-light to save fuel.

Safety

Canister: The few problems that occur are usually caused by incorrectly connecting stoves to canisters, and can be avoided. Knocking stoves over can cause flaring. No risk of spillage.

White Gas: Large flames during priming can be alarming to some people and can present a fire hazard if care is not taken. Some risk of spillage when filling. More likely to go out than to flare if overturned. Leakage of fuel into your food supply is disastrous.

Ease of Adjustment of Output

Canister: Easy on all models.

White Gas: Easy on Coleman/Peak 1 models and MSR DragonFly. Takes a little practice to adjust to low flame with MSR Whisperlites, Sigg Fire-Jet, and Primus Himalayan Multifuel because the valve is distant from the burner.

Simmering Ability

Canister: The smaller the burner diameter the lower the flame can go before it dies, but most can be turned down to, and will hold, a low simmering flame. However, the smaller the burner diameter the more localized the heating and the greater the likelihood of sticking with pots that spread heat poorly (thin stainless and titanium).

White Gas: "Roarer" burners of MSR Dragonfly and Primus Himalayan Multifuel can be turned down to a candle-size, but sooty flame. Coleman Peak 1 models are still quite hot on the lowest setting if tank pressure is high. MSR Whisperlites can be turned down to a very low flame with practice and if tank pressure is not high.