I play a lot of Dr. Liang. The strongest part of his kit is the Titan/Repair Drone combo. If he survives to that point, he rightfully should be in an advantageous position. This is Dr. Liang's reward for getting to that point.
This is because in the early stages of the game, the repair drone is pretty bad. This is when Dr. Liang is weakest and you should generally try your best to capitalize on this weakness to build an advantage. Dr. Liang may still be able to pop out the Titan combo, but if you achieved an early-game advantage, you should to be able to finish him off before he sets up all the pieces necessary for his late game advantage.
I am a little confused people are now saying the Titan of all things is overpowered, having faced plenty of Titans while grinding to my current Level 10, I just really don't see how they can be considered overpowered unless of course you are trying to spam tanks into Titans which is doomed to fail or unless the opponent has gotten so far ahead they are fielding Wolverines with Titans or massing Titans. A lot of the complaints I am seeing is that people are trying to clash Sandstorms into Titans and excepting their Sandstorms to win which they find shocked it doesn't melt like all other vehicles, well it has to have some other counter considering it shreds all other vehicles and aircraft. Like JadeXayan said even without direct counter units such as Zone Troopers, Orcas or Jumpjet Troopers ; the basic missile squads or laser troopers still do a fairly decent job of scraping a Titan especially in pairs of two and if you are running into the Titan often it may be a good idea to invest in training/leveling up your missile squads to increase their effectiveness against Titans.
Now I will admit I have only faced Dr. Liang a few times that was attempting to field the Titan with Repair Drone combo and to be honest it didn't really seem to boost their survivability that much and they are far from being this indestructible monstrosity that people seem to be making it out to be. They all but seem to disappear once hard counters open up like the GDI Orca at level 6 or GDI Kodiak at level 8. Especially if you can get your hands on the Orca or Kodiak as they deal massive damage to Titans while having no fear of reprisal from them.
While I will agree Titans can seem imposing they are definitely not unbeatable and likely if the enemy is successful in fielding them in mass or in combination with Wolverines then either the game is stalling out too long or the enemy is managing to out resource you as these units do not come cheap at 130 Tiberium each being one of the second most expensive units in the game tied with the GDI Kodiak. As Diablosdungeon mentioned Dr. Liang seems to be geared to the late game which to be fair the game should not be lasting to the point that the good Doctor is able to spend 130 plus the 60 a total of 190 tiberium to field this combo unless of course you lost the early game and it has now come to a late game brawl which you now would be at a disadvantage if that is the case
On top of the other advice here, also consider having a talon in your kit. It can easily dispose of repair drones, and the titans can't hit it, so it can contest points just by being there. Never know when they'll come in handy, got mismatched against someone higher level than me who had kodiaks and talons saved the day there.
Titans really aren't worse than rockworms, it's just that GDI has zone troopers and orcas as a rare drop and banshees are common so nod has more newbie friendly options.
