If I'm using film, it's probably in a camera without a meter, just because I do old cameras for fun. For those times, I use a Sekonic L-308 for incident light. Even if I'm using my Mamiya 645 Pro, which has a meter in the prism finder, I may still use my hand-held meter.
With cameras that were built for rapid, eye-level use, like my Canon A-1, I often use the TTL meter if there is one; but you have to use it with some judgement. I often meter a 'normal' scene and keep the reading for the odd shadowy scene I want to photograph.
My mirrorless digital has plenty of modes of TTL metering, and I think I have probably used all of them, and hand-held incident-light metering too. Something I can only do with the digital is leave the camera in manual, and rely on the exposure-simulation in the VF, which I find isn't bad: take the photo when it looks right.
'Sunny 16' doesn't serve the UK very well. There are at least 50 shades of overcast. Right now, it's half-past nine in the morning, and I have the house lights on, the cloud is that thick. Rainy f/2.8 out there, maybe.