TL;DR: Engineering allowed me to turn the much-maligned Alliance Challenger into the most fun ship in the game (for me). What ships have you engineered for fun/creative builds?
I've played nearly 800 hours of Elite, and for about 700 of those hours I completely ignored engineering (the grind is poorly designed, as we all know). Big mistake!
For a while, I've wanted a ship that could serve as a good platform for pack-hounds. They're super fun missiles, but they create a ton of heat and can only reliably be used in any numbers on ships with decent heat management. Enter my new favorite: the Alliance Challenger.
People hate this ship: it's derided as a worse version of the Chieftain, and in most cases that's a fair appraisal. Not so when it comes to pack-hounds! Look at
I strapped on 1 Large and 2 Small long-range thermal vent beam lasers, 3 pack-hound missile launchers, and 1 corrosive turreted multicannon. Most medium ships would melt when trying to figure 3 pack-hounds at the same time. Even my big ol' Federal Corvette required careful engineering to manage that many pack-hounds, and what's more, the hardpoints on the Corvette meant fitting 3 packhounds would require replacing the Large hardpoint with a medium weapon (bad idea). The Chieftain has the same problem: it can only fit three pack-hounds if you're willing to sacrifice two large hard points (even worse idea). The Challenger has no such issues — and the hardpoint convergence is beautiful. The top large hardpoint is surrounded by three small hardpoints in a delta formation (two above and behind, one directly in front and below — between it and the cockpit). My three thermal beams are all fired from just above and behind my cockpit (the Large + the two Smalls above/behind it), and the corrosive multicannon is the Small hardpoint directly above my cockpit (turreted and linked to the pack-hounds to give them even more kick). The three medium hardpoints are arrayed in a triangle/delta directly below the nose of my ship, under the cockpit, so my missiles all swarm in from more or less the same point.
With proper engineering of the power plant, power distributor, weaponry, and such, I was able to create the single most fun ship I've ever flown. I paint my targets with my thermal vent lasers and then when their shields are gone (and my heat — already resting at a low ~35% — is reduced to 0!) my pack-hounds shred their engines so I can dismantle them at my leisure. I've tried similar builds on the Fer-de-Lance, the Chieftain, and the Corvette, and the Challenger — viewed as one of the worst ships in the game by some — is the most fun of the bunch (and it isn't close!). Engineering allows great flexibility for playing around with various builds and tuning your ship to excel in whatever role you choose. Even though the grind is a pain, the end result can be extraordinary — and more importantly, that result is defined entirely by your vision for the ship in question. Engineering lets you decide what kind of ship you want to fly, and then to make it a reality.