Diesel/Steam?
Part of my time, (apprenticeship), was spent on triple up and downers and horizontal dual expansion engines in Cardiff docks, I've also turned LP piston and junk rings rings, six foot diameter, do it wrong and they come out square! The boilers, twin steam and water drums, were coal fired, (lumps not PF), with weight loaded safety valves, the boilers dated to 1890! still at full load in 1958.
My first trip to sea as a j/e was on a four cyl Doxford with steam auxiliaries, the beast broke down after 21 hours full away, and rarely got a 24 hour run after that! It was 8 months 12 days and 17 hours of purgatory!
Thereafter I sailed on steam turbines, much safer more comfortable and cleaner, even though some vessels required 17 hour days, it was much better than removing scraping and refitting ALL bearings on a Doxford, dead ship, at sea off Nicaragua! Steam is always best in my view.
As a Cockburns valve Engineer, I worked on most of the big liners and lots of the big(then) BP and Shell tankers as well as lots of FoC steam tankers that had once been owned by the big names in earlier times, even then the steam gear was in good(mostly) order and generally trouble free. Who's heard a Full Bore safety valve, going off like a Bofors? Not much of a problem, if one has all the bits to fix it! Had to sail a tanker from Bremerhaven to Rotterdam once because the chief didn't trust the safeties, 36 hours in Rotterdam and all was fixed, chief as happy as Larry!
Steam is the best, just like Watt, (not who), said!