Frothy's tier list pretty much matches my own. I want Titan's like Scorch and Ronin to be good but the sheer damage being dealt out by Titan's like Tone and Ion is just too oppressive to push through.
Additionally, something he doesn't touch upon is how the Titan's synergise with one another, and how others don't. Tone and Tone, or Tone and Legion, Northstar, etc, synergise very well together to hold a lane. You can dish out large amounts of damage while shielding yourself from a large amount.
Someone like Scorch doesn't offer awfully great synergy with other members of his team. His gameplan doesn't match there's so it's hard to find cross-utility. Tone's shield can't protect him as he tries to push up, Ion, Legion and Northstar find themselves at cross purposes with Scorch and Ronin. They want to hang back, play a war of attrition, and hold their lane, while Scorch and Ronin want to get in close and dish out damage.
In theory their weaknesses would be mitigated with stealth, flanking and positioning, when you consider the maps at the scale that the Titan's fight, there are very very few objects that obstruct sightlines, very few options, very few routes that you can take. It's very easy for even a half competent team to lock the entire map down, shutting down the entire map from these close range Titan's and forcing this mid-long range battle of attrition as Titan's poke at eachother from mid-long range, trying to minimize damage to themselves while chipping away at their opponent.
This is the dominant playstyle of LTS and Tone, Ion and Legion are the only Titan's that fit this playstyle. The map design and nature of the game suits the way that these Titan's want to play, so it's very obvious why they'd be more powerful. Simple adjustments to Scorch and Ronin's efficacy will not charge this if they are not drastic. Ronin's gameplan does not fit the current meta, there's no reason to want to overextend into a lane with a single Titan.
I think Scorch needs a little bit more damage output with his primary, to make him a bit more versatile. He's not in too bad of a place but he needs to be able to at least threaten with well placed shots at mid-range. I also think Scorch should be able to spread fire through Tone's walls. Tone is an absolute hard counter to Scorch right now because he does not deal high direct damage, it's dealt by fire AoE. The issue with that is that he deals close to zero damage to Tone's walls, meaning he can't push on Tone. When the most popular Titan in the game is your absolute worst matchup, that makes you seem a lot less viable than you would otherwise be, so addressing that matchup may make a big difference for him.
It'd also be nice to see a little bit more flexibility with his kit. A dash on Scorch is essential, for instance, other Titan's don't feel quite so limited. Perhaps Scorch should have a dash by default, that would certainly help him get close to his opponents. At the moment this is his issue. Getting into his space carries too much risk, and he ends up dead before he gets there. There's only so much fire shield can do.
Ronin is the same but worse really. His health is too low, there's too much risk associated with any over extension into a lane, you die instantly and making matters worse you aren't rewarded for the successful flank, even if you get it. Even if you manage to sneak into a lane and push you don't deal enough damage to win most 1 vs 1 encounters. Your health is too low, and if the opponent see's you coming you will generally trade. That shouldn't be the case, Ronin has to work to get into his optimum range, he should be rewarded with a significant battlefield advantage if he gets there successfully. Ronin could use a little more health to mitigate the increased risks a close ranged Titan of his style has to take, and a significant boost to damage.