Seiko Tunas - especially the 1000m ones. I used to think they were clownish, oversized nonsense, and may even be on record comparing them to a manhole cover on the wrist. I didn't like the shroud and when I eventually did try one of the SUN019 kinetic GMTs years ago, I hated it. Too high, too clunky, just... Ugh.
Then came the re-issued Arnie, which I tried against my better judgment and unexpectedly enjoyed. Then a Darth, and now a Field Tuna as well. So in the space of two-and-a-half years I've gone from being a Tuna refusenik to having three, and desperately wishing I had decided to hit "buy" on the spring drive one on which I had an option a couple of years back.
I especially love the Darth - it's light, it's supremely comfortable (lug-less), it has a Kanji day wheel which I thoroughly enjoy, it's accurate, and it has stealthily become my grab-and-go standard. I'm trying to resist the impulse to find a golden one, and the limited-edition blue one, and, and, and...