The mainstay of the titan legions. More responsibly for Unity and Heresy than the space marine legions themselves - arguably. They can lay waste to both armies and cities alike, and can do so on airless rocky moons and verdant planets alike so long as the ground beneath them can support their mass. Their only true enemy is others of their kith and kin.
See the notes that I made about the Warhound Titan in the previous post to begin with.
I last reviewed the Warlord Titan in 2016, at that point it cost 2750 points (now 3000 points which is still more than fair) and cost GBP 1240 - now costs 1185 before the weapons which would take it up to the region of GBP1537.50 (volcano cannons and missile launchers). As I stated in 2016, I would like you to have a good hard look at those numbers. Are you going to use it in a game? Are you rich enough not to care? Or merely display it in your home somehow and hope that your toddlers (if you have any) don't try to play with it as an equal (in size at least)? I don't yet own one myself, but have often toyed with the desire to purchase one, I will freely admit.
With a game breaking AV=15 on two faces, a whopping 30 hull points, 6 void shields, 5++, and all the usual titan rules you've come to expect, I'm not even sure how to bring a Warlord down short of fielding one against it myself. Other than that, we get to choose two arm weapons and two carapace weapons. And yes: there is choice here. The weapons are all viable in various combinations. For the arms, I like the sun fury plasma annihilators and the bellicose pattern volcano cannons most myself. I don't like the close combat weapon (the shooting is better, and you've got a great stomp attack anyway and can't be locked in combat regardless -- even by another titan. Hence I think taking ranged weapons is better, but equally, it is the size of my own hand, and also works well in full sized games of Titanica). For the carapace, I like all options. However in second edition, we are missing the vortex option - why oh why???
Weaknesses.
None. Even the fact that it explodes magnificently upon engine death can be a strength.
Builds.
To be clear: you can not truthfully go wrong here. These builds are merely suggestions.
Warlord Battle Titan, 2 Apocalypse Missile Launchers, 2 Sunfury Plasma Annihilators.