Okay, this will be a long post because I seem to have a mild addiction for light meters. I have handheld Sekonic spot and reflective meters for medium and large format work. I bought a VC II meter when I got my first Leica (M4) last year. I actually like the shoe mounted meter concept. It’s separates the electronics from the camera and provides a nice methodical shooting process. All that’s said above about thinking through the exposure applies to all meters, and the VC meter gave generally good base readings for B&W. I sold it because the slipping ASA dial drove me nuts, and it’s a two step process: turn on, adjust leds. I did like that, once set, you can see equivalent exposures at a glance.
I’ve also bought via Kickstarter the Reveni Labs meter and the KEKS meter. Both are very good and both have their own issues. The buttons on the Raveni are tiny. I use it on a IIIf with a dual shoe mount for a 28/50 viewfinder. Really like that setup. The Raveni weighs nothing, give the same readings as my Sekonic handheld, and the LEDs are really bright - easily visible in backlit sunlight. Battery life is a weak spot - must be fresh to work properly. Still, I like it, and will probably get another for a recent TLR purchase.
I use the KEKS on my M4. It’s weaknesses are its LED, which washes out in backlit sunlight, and that you can’t adjust the meter to avoid intermediate readings (1/300 @ F8), (at least I don’t think you can do that). Its USB rechargeable battery seems to last forever on a charge.
Overall, I like these LED meters better than the VC meter because the reading is one-step and instantaneous. I don’t find it too tough to calculate the equivalent exposures in my head, but you can fiddle with the buttons if needed.
I’ve also bought, via Kickstarter, the Lime light meter, which should ship soon, and the Raveni Labs spot meter, which is a way’s off. I can report back about them.