Okay so I've been playing since November and for 3 months now pretty much exclusively LTS. Attrition and the other game modes are great too but nothing beats titan on titan. I think after the last update the titans are pretty balanced. One of the best parts of the game is how many different play styles there are.
I can say now that I'm pretty damn good with Ronin. Consistently get over 50k damage and many times 70-80k routinely. It's not a hard counter to Tone, but it's a pretty damn good one, especially when you have to use teamwork. The sword wave kills the Tone shield in one shot and then you can go in to the battle and just cause mayhem while your teammates light it up from far. The wave is also great for removing Legion's shield. Close up, it can fuck up any titan except Scorch, and it's excellent for hit and runs. Phasing behind the enemy team and throwing down a smoke, they will get wrecked unless they have backup on the side. Phasing into another titan and automatically dying is infuriating though.
Tone and Legion are probably the easiest to use for new players, experienced players do crazy damage though. I didn't realize how good Legion was until I started playing with some good players. Legion can eat health from long range, and mid range power shot x 2 is deadly. Knock back makes it even more lethal. Equipping a dash is pretty much necessary. Smart core is cheap as fuck...arguably the best core on LTS. Even up close it's hard to fight a legion that has smart core on.
Ion is also great, but it has to be used strategically which probably makes it harder to use. Laser shots are deadly and even the main gun can pull off a good amount of damage. The shield is amazing when used properly and it's definitely a hard counter to Legion, a good Ion player will never lose in a Legion fight. I try to kill Ion players first because its core can kill an entire team...and it can get its core pretty fast.
For scorch, I think if you're a really good scorch player you will end up doing the most damage on your team in a lot of maps. You can deny entire sections of some maps. The shield does CRAZY damage, and it's really hard to beat if you're a Ronin. Hit and run is a key tactic if you're fighting scorch and you really need to use its lack of speed to your advantage. I was surprised at the range of flame core too...that thing goes far. Having a scorch fighting beside you lets you take more risks too.
Northstar is probably the hardest to be really good at, but it's amazing when used properly. You can go entire games just getting wrecked from far and there's pretty much nothing you can do. Really good for countering Scorch and Legion. Good luck trying to chase it down too...even when you're close, the tether traps are going to stop your progress...those things are annoying as fuck and they can change the outcome of a match once you get stuck in one or two and it's too late to do anything. It's definitely risky flying around and even using the core, but that can be mitigated if you're playing smart and using your speed to move all over the map. This is a game where movement is key. Northstar is not only the most agile Titan, but it can also fuck up the movement of enemy titans.
Just my thoughts...overall I think it's pretty decently balanced at this stage. If you're playing against good teams, you will need to communicate with your teammates if you want a chance to win, which is why it's kinda hard if you're playing solo.