There is a reason why Hunters are considered the champions of soloing as they are essentially their own Trinity with their pet (Pet Tank, Hunter Heal/cleanse, both DPS) and Hunter pets don't have the same Threat issues. They are a little hard to multibox multiple optimally but you can do 1 of them optimally and the other decently. 2 Hunters + Healer can do a lot so there is a lot of merit in that recommendation. That being said Hunters are not needed in great numbers in raids and likely at most you will be able to bring 1 hunter or 1 healer.

Another interesting 3 toon combo that has had success soloing dungeons is 2 Warlocks+Paladin (with the Paladin helping manage Threat). Unfortunately people have reported issues with Warlock Pets tanking due to losing Threat generally and the only real successes reported thus far have been with a Paladin in the group. It should be noted that that Trio (2 Warlocks+Paladin) was able to clear Scarlet Monastery Armory at Level 39 and that Scarlet Monastery at Level 40 and while that is very promising that Trio hasn't gotten to cap and cleared the higher dungeons yet. You can read more here:

https://www.dual-boxing.com/threads/...l=1#post423588

You obviously would be able to take to raids 1 Paladin or 1 Warlock and may be able to bring 2 Warlocks from time to time. This would be more likely if you get involved in catch-up raids or farming raids where they run the easier content to gear up new people and to make gold... Maybe at some point, if you build up trust with 2 Warlocks, you could bring an Improved Concentration Aura Paladin with your Warlocks.

As mentioned 3 Mages can join groups and finish dungeons if you find a good tank & healer. You may also be able to 3 box them in Raids (I would start with 1 in the main progression raids and try to work additional ones first into the catch-up/on-farm raids).

3 Warlocks are somewhat less DPS than Mages at least until the later phases and their numbers in raids are typically less so if you really want to raid Mages are the better choice.

In case you are curious the following is the best indication of class demand for raids:

https://www.reddit.com/r/classicwow/...d_composition/

I have not seen yet any update for raids on live that shows anything different but would love to get any info if anyone comes across it.