After a series of LTM cameras from the IIf, IIIf, IIIg, Canon 7s, and Bessa R, I finally graduated to a Leica M7. Of the LTM cameras, I'd say that the Bessa R is the easiest to use with its built in meter, and excellent viewfinder.
The one thing that I like best about the M7 and M5 are their decent sized shutter speed dials. (I've not tried the M6TTL, but it's similar to the M7 in shutter dial size). In the meantime, I got the M2, M3, M4-2. All of these have tiny, unusable shutter speed dials. True, the iIIf and IIIg also have small shutter speed dials, but since you need to lift them up to change speeds anyway, it's not a problem. Only when you put the Leicameter on these cameras do they make ergonomic sense. Then you have the big overhanging shutter speed dial similar to the M5. To me, this is the fatal flaw of the MP and classic M6. They have no way around the atrophic shutter speed dial.
Initially, I was underwhelmed by the M2 and M3. However, their solidity and quiet elegance have started to win me over. I like the rewind knob better than the crank on the M7 and others. At least they don't roll back when your hand slips off.
I also appreciate that the M2 and M3 have self timers. Those that don't have them are really annoying when you want that feature. I have an Autoknips spring wound self timer for the M7 and M4-2. It's fiddly to use, but it works.
So, of the Leica M cameras, my personal ranking for use is M7, M5 and M4-2 with Leicameter MR-4.
Having said that, I feel that Leica is a huge money pit. For the price of Leica gear, you can (and I did) buy medium format gear. Rolleiflex 3.5F, 2.8F, Voigtlander Bessa IIIW and the Fuji 667 folder. Even the Voigtlander Bessa RF and Kodak Medalist II 6x9 format cameras. Leica lenses are superb. However, on a 24x36mm piece of film, there's only so much you can do. These medium format cameras with their also excellent lenses can really put out an image with smooth tonality and tons of detail.
So, this is my long and rambling way of saying that you've tried the M3 and it isn't for you. It's not the end of the world. There are many other cameras out there for you to try. Every camera has some quirk that you have to either learn to live with, or give it up.
As they say in fishing, catch and release.