If this is a weird topic, then I'm weird b/c this is one of those things I've thought a lot about long before it was a topic
To me, it depends on the subject matter. Most aircraft are too huge in true 1:18 for play or display or my budget. For example, the Skystriker (F-14) is 3' x 3', and the Raven (SR-71) is 6' long in 1:18! Yet you hold a Joe Skystriker and it just feels like it fits. Most of the PTE jets (F-18, A-10) have that same vibe. The True Heroes (TRU line) F-22 is another gem in that category - it's probably closer to ~1:32, but I can squeeze a modern Ace fig in there and the cockpit area doesn't even seem abnormally large compared to the rest of the plane.
But for tanks, shrinking things like the mighty M1 Abrams tank into a dinky MOBAT just doesn't work for me. As shown by the Patriot Grizzly or BBI and FOVs M1s, truer-scale tanks can work just fine in 1:18, and they look a lot more big and mean that way!
The Joe Warthog is another big win - the real thing is a lot larger, but the Joe version still very comfortably holds 3 crew + 6-8 passengers! The Equalizer and Rolling Thunder also get a thumbs-up.
A modern fail to me is the ROC Cobra Gunship. While it is not a real-world vehicle, the "real" version in the movie was just so much more than the toy version. A modern win to me is the recent HISSes - small for a true main battle tank, but as fast recon light armor, they still give that visual appearance of packing a lot of ooomph in a small package.