No, I don't have an obsessive disorder with giant robots... why do you ask?
My "re-inventions" of the Titans. In my head-canon, these are all Tigrus-pattern titans, from the home Forgeworld of Legio Solaria. Bit of a halfway house between the more common Mars-pattern, and the Lucius-pattern.
I've tried to make them "sensible" in terms of weaponry, especially the point-defense systems which Titans seem to habitually struggle with. They're thus decked out with heavy bolters and lascannons for dealing with what i will call "tabletop level" threats. Most of the Battle titans also have at least one "tertiary" weapon system (typically in the form of Arachnus heavy lascannons) for dealing with slightly bigger stuff. They all also have some form of air defense, as it always seemed to me that your average Titan was reliant on a bit of good luck and voids to avoid being bombed into the 43rd millenium, much like the demise of the battleship in WW2. There is therefore some flavour of Hydra flak battery on everything from the Warlord up, with the Reaver and Warhound instead relying on weight of fire from autocannon arrays - the Reaver having 4 storm cannons (16 barrels), and the Warhound settling for a three-point twin-linked autocannon array.
The sizes of these titans have been scaled roughly from a human, the assumption being that the carapace "flat surface" (the bit between the battlecannon turrets that the big towers sit on) is big enough for someone to walk around in. That gives me the height of the Imperator as a little bit over 270 metres / 680 ft to the tip of the rear spires.
The Imperator is, obviously, armed to the absolute teeth, based on both the old school Imperator from the 90s and the Apocalypse datasheets which are floating round on the web. I beefed up the plasma weapon until it looked right, taking inspiration from the Warmaster Suzerains, and the Warlord Sunfury. I re-imagined the Hellstorm cannon - the fluff can't decide whether this is a laser or projectile weapon, so I decided to make it a huge neutron particle weapon. Each of the carapace turrets is armed with a battlecannon, and either an Iliastus Accelerator turret, or twin-link lascannons. This is the closest thing to "ENUFF DAKKA" that I could feasibly fit on the thing, without dedicating it to Mork and Gork.
I scaled the Warmaster to fit between the Imperator and the Warlords in scale, based roughly on the size comparison image that GW put out - the Warmaster is therefore 130 m to the top of the Revelator missile array on the carapace. The Hellstorm Destructors that the "Forgotten Kingdom" is armed with are my own invention, being a scaled down version of the weapon on the Imperator. I'll be tweaking these again into a smaller version, probably twin-barrelled, to mount as an arm-weapon on a Warlord.
I then based the size of the Warlords on the cover of "The Burden of Loyalty", which shows them coming up to about the weapon-mount level on the Imperator. Thus, the Warlords are, to the top of the vents adjacent to the carapace weapons, 101.6 m / 333' 4".
The Reaver and Warhound were scaled appropriately from the same image - 80.9 m / 265' 5" and 47.7 m / 156' 6" respectively. I don't have names for any of these yet, so I'm open to suggestions.
These sizes are, obviously, quite a bit bigger than the quoted sizes that GW have put out, but seem to be more fluff-compatible.
In the group shot above, you may be able to see a small smudge between the feet of the Scion... which is a 9ft tall Mk-X armoured Primaris. The giant robots are, therefore, quite giant!
Still got quite a lot of detailing to do. The Reavers and Warhounds are, obviously, in a much more "unfinished" state.