I would not buy an expensive canister light without trying it in the water on the type of dives you do now. Lights are somewhat subjective in terms of color and focal point. I spent a lot of money on a canister light from one of the best companies and ended up selling it a year later because I didn’t like the beam appearance, for the type of diving I do. I now use two handhelds that are not nearly as well made but they work, cost about 1/3 the price, and I like the way they look in the water.
If you are a single tank diver, it’s almost inconceivable that you wouldn’t get sufficient burn time from a handheld light. If you’re diving doubles (i.e. longer dives) then you could consider a canister light but you need to choose top gland or side gland depending on your gear configuration, and if that changes, so does your canister light.
The comments about the handheld being heavier/bulkier in your hand than a canister light head are valid, but again unless you are doing very long dives, you can get by with a pretty compact light.
The comments about not being able to lose a canister light because it’s attached to you are also valid, but in the type of diving I do (cave) you learn to attach everything that’s not under your control, and in the last few years in which I’ve been using the handheld, I’ve never dropped it or dropped a backup. I use the razor hand and helmet mount so the light is rarely in my hand, more often attached to one of the mounts.