This is purely my opinion so pleasae take it as that.
Your "main" torch needs to be indestructable. made of metal,Have TWO o ring seals,Have battery sizes that are readilly available,Have a slide type on /off switch,Be LED,Have a Pencil type beam,be small enough to go in a BC pocket.
MY reasoning is that your main torch stays with you all the time, great for looking at the roof of a swimthrough etc.useable for (on occassion) rapping your tank to get your buddies attention,metal to take the hard knocks being a bit clumsy can cause 2 o rings for safety,Readilly available batteries because yea you might have super rechargeables etc but on a long holiday trip being able too just buy a couple of batteries is great.Pencil beam for at night is ideal for signalling and again looking at stuff under rocks.
Incidently diving tropical night diving I slide it into the sleeve of my wetsuit so my hand is free.
The number 2 torch, Its for night dives so doesn't get as much use.This one I'm happy to go with a bright colored plastic casing.I like to go for triple bulb and a far less focussed beam.otherwise the same rules apply.The more light the better so usually its 8 A batteries.
I PERSONALLY like the pistol grip torch as my second torch but thats because the hand position to hold it is more natural than the tube type
-My wrists are full of titanium so its uncomfortable having my wrist angled.
The big torch I find bathes the area in light like a fluro bulb rather than an intense focussed beam.
Lastly Ive got one of those LED lights that replaces your yoke screw.I only use if for night dives but my buddies thought it was great and easy to see