Ok, so the last few chapters have basically introduced the idea of "titan customization". Rod made the point that the titan he made for historia was ideal for combat and the result was a massive monstrousity which was too big to support itself and had heat so intense it was on fire and caused things around it to fire up.
We also saw there was a vial with the armor powers which eren lacked earlier. Presumably there would be other vials with other characteristics... perhaps the scream, size... And it is possible to make titans by combining the liquids in the vials.
Now, we have seen a number of titans of different sizes and characteristics. Annie's was a little over 15 meters and could call her armor. Reyner was constantly armored. Berholt is 60 meters tall but at that point we see that there are issues with being so big. He is incredibly hot and his movements are rather slow. In many ways he is less dangerous than other titans, with him actually being more easily managed that reynor or annie. The beast titan was covered in hair, is well bigger than your standard 15 meter titan and has been said to be very powerful.
So... knowing what we know, what do you guys think would be the ideal titan? How big? What abilities? Perhaps rod's titan would be invinsible due to being on fire? Or maybe other titans would have alternate ways of dealing with him.. I guess berholt could just step on his nape...Or reyner could smash his nape by simply running into it. Although reyner would perhaps put himself in danger if he does that.
I think Rod's titan was incomplete since he didn't take the titan syringe thing through normal means. Iirc, berthold could control his fire thing and increase it when needed (he did so when he appeared at the wall and eren tried to strike him).
Ideal imo could be something like 20-25 meters so they can retain decent speed while also having a fair amount of strength. Fire could be very useful if it can be controlled and if there's enough speed. I think it's a better option than the armour. When Eren and Reiner fought, Reiner's armour kept up but Eren could attack until he finally got past it. Such an option doesn't exist with fire though. Each attack is dangerous whether the Titan retaliates or not and one can probably only get a couple in before being too burnt to risk any more. If the Titan is also has decent combat ability, it could be a real problem.