The 41.5mm size works for most; the steel case is versatile and tough; the lume is abundant enough to work well; the alarm is a friendly complication with many uses. Also, with an internal dive bezel and locking crowns, the watch is suitable for light-duty diving.
I have personally handled all versions except the platinum (I remain hopeful), and this is the watch that people with Rolex money should buy pre-owned. Prices have settled, and there's no losing if you buy privately and sell privately. JLC's service costs are shockingly reasonable (I paid $910 for a full overhaul of my Amvox2 chronograph, among other fair charges). For $5,500 (steel with strap) to $7,500 (steel with bracelet), this is a tough watch to beat. You could have one of these on a strap for the price of a new Rolex Oyster Perpetual.
As for reliability, I have found these to be tough. Caliber 918 isn't terribly sophisticated, but it's tough, precise, and the alarm is potent. Across dozens of examples examined, I've found no water intrusion issues. The Compressor crown seals age better than their screw-down crown counterparts because the Compressors only "compress" rather than thread through the crown seals.
Moreover, I've long suspected that the Compressor crowns offer more water security when not locked than a screw-down crown that's out of its sleeve. This is important when buying an older watch, because many "dreaded previous owners" (DPO) shower, bathe, and even swim after setting and forgetting their crowns. A watch that's smarter than its first owner has some advantages for second and third owners.
Best,
Tim