The A-10C has laser guided 70mm rockets too now. Whether they would be "better" than Brimstone (and I take it you mean at least DMB level Brimstone) depends on the circumstances and the target.
Advantages of 70mm laser guided rocket.
1. Considerably cheaper - probably only 1:5 the cost of Brimstone.
2. You can carry lots of them*
3. They have comparatively low collateral damage.
Advantage of Brimstone.
1. Bigger, multimode warhead capable of taking out MBTs whereas 70mm would generally have HE FRAG and be limited to non-armoured targets. Not sure if HEAT still available, but that would be limited to anything up to older IFVs
2. Vastly better range.
3. Ability to attack autonomously (killbox capability).
4. Ability to attack multiple targets near simultaneously.
5. Not weather limited vs AFVs.
6. Non line of sight capable.
If you are blowing up technicals in Iraq from outside the MANPADS envelope, the 70mm rocket is the way to go. On a dark rainy night in Poland vs hordes of T-80s, Brimstone would be infinitely better.
To designate, all current and all likely small, cheap UAVs are going to rely on a comparatively high bandwidth connection to a human controller. If you are going to go truly autonomous with small drones (and despite repeated refutations by our side, someone on their side will do it and we will use that as a decision to follow), you are probably better off putting a warhead on the drone.
The problem with launching missiles off the back of a Toyota is the Toyota has to be in the right place at the right time. That was the primary reason EFOGM was cancelled. It couldn't displace fast enough to re position to counter enemy armoured incursions. I don't discount the idea, but it needs a missile with a sensor in it - something like the Korean truck mounted Spike NLOS, although that has a vulnerable RF datalink. Spike LR dual-mode on a Landcruiser makes a certain amount of sense.
*I have so far only seen them used with the 7 round launcher, but, as the APKWS II locks on after launch, it can use any launcher so there is no theoretical reason you couldn't see 19 rounders used. If the F-4 had still been in service we could have seen a loadout with 12 x 19 round launchers for a total of 228 guided rockets per airframe.