Curious about Toggles

In general, you are expected to run most toggles simultaneously. Very few toggles are mutually exclusive, and those that are tell you what they are incompatible with in their descriptions. A few toggles are very endurance intensive to run, and these are usually intended to be run only for a short time, but aggressive endurance reduction/recovery builds can sometimes run them full-time.

When you are low level, you may not have the endurance to run all your toggles simultaneously. Slotting attacks for end reduction (high priority), slotting toggles with end reduction (moderate priority) and getting Stamina (if/when you can) all will alleviate this issue, as will various special IOs or accolades that improve your endurance total and recovery rate.

If you find you cannot run your two toggles together until you get better slotting, you should probably prefer the melee defense toggle. Most mobs are more damaging with melee attacks, and/or have more of them to cycle through. Making them miss more in melee is probably more valuable. On the downside, many low level mobs debuff your defense powers with their ranged attacks (bullets often do this), so your results may vary depending on foe.

Defense powers work by checking the attacks "types" (such as ranged or melee) against all your defense values. If you have any defense that work against the attack's types, you benefit from the highest of those defense values. As far as I know, there's no such thing as an attack that's flagged both ranged and melee. Most attacks combine one position type (melee, ranged, AoE) and one or more damage types (lethal, smashing, cold, fire, energy, negative, or psionic - there is no "toxic" attack type). A few have only a single position or a single damage type, but not the other.

Defensive/Resistance toggles are generally a fire and forget; typically you turn them on when you log in and then leave them run. Deflection provides Melee defense and Smash/Lethal resistance while Battle Agility provides Ranged & AOE defense so they protect you from different things. Attacks are generally flagged as being Melee attacks (punches, kicks and so forth), Ranged attacks (blasts, gunfire and anything from range) and AOE attacks (Area of Effect, attacks that can hit more than one character. Things like Fire Ball and the like)

Because of this Deflection protects from punches, kicks and the like but doesn't protect you from a mob tossing energy blasts at you from 20' away. Likewise Battle Agility protects from those attacks but doesn't help you against punches & kicks. Once your build matures you'll be running both shields plus other toggles as well to maximize your survivability.

HOWEVER, I'm going to guess that your brute is still low level? Pre-20 and Stamina? In that case endurance will be an issue for you... I generally don't get the Ranged/AOE shield until level 22 and deal with the Melee shield only until then. The reasoning is that as a Brute you'll be fighting mostly Melee mobs and before Stamina endurance is tight, particularly with a brute constantly chasing Fury.

My suggestion for the early levels would be to slot endurance reduction in your shield and mainly slot accuracy and endurance reduction in your attacks. If it were me I'd probably start a SS/Shield brute something like this:

1. Punch & Deflection
2. Haymaker
4. True Grit
6. Hurdle (Fitness pool)
8. Knock Out Blow
10. Active Defense (eventually 3 slot for recharge)
12. Combat Jumping
14. Super Jump
16. Against All Odds (endurance reduction, one is probably enough)
18. Health (Fitness Pool)
20. Stamina, 3 slot for Endurance Modification.
22. Battle Agility