I got a model 3 back when they first came out. A few years later, I traded it in and got a model 1 when they were $20 at Funco Land, I have no idea what revision. A few years after that, I traded in my model 1 and got a model 2 (with bad audio, although I was clueless to that fact back then).
In more recent years, I ended up with a few different model 2's and a High Definition Graphics model 1 without TMSS. At that time, I wanted to slim down what I owned and forced myself to choose between keeping a model 1 or 2.
I actually made a ton of clips, recorded from the sound tests in a few games, between the model 1 and the two model 2's I had. I spent a lot of time listening back and forth between my non-TMSS model 1 and my 2/3 board model 2. I can get why people say the model 1 sounds "better" or it's "the way it's suppose to sound" but honestly, the later model 2's sound alright. Different, but neither better or worse.
I ended up keeping the model 2 because I didn't care about the difference in sound. The 2/3 mobo model 2 doesn't have distortion like the other revisions, and that was the important part. With the model 1, I noticed that there would be some distortion when the volume slider is at 10, which is kinda annoying (I know you can set it at ~7, but I find that to be annoying). Also, the only way to get stereo audio is to use the front headphones jack, which is ultra annoying to me. You need special cables or adapters to do what the model 2 can do with just the standard cable.
My other deciding factor was the Sega CD, which I don't use very often, but I had to consider this since I own one. The model 1 Sega CD looks bad ass, but I'll never get one due to the issues they have, while the model 2 Sega CD don't have those issues. So I'm forever sticking with the model 2 Sega CD. The model 1 Genesis with the model 2 Sega CD is just awfully long. And by that I mean, it's AWFUL how long it is. I also don't have the extension thing for a model 1 Genny, so mine would have to hang over the edge and look even stupider. All that combined is why I chose the later revision model 2 and got rid of all my other Genesis consoles.
MOST recently though, I got another HDG model 1 (this time with TMSS) from a friend and decided to keep it. Currently, I use the model 1 with my HDTV (I have a Framemeister and an RGB cable that has a 3.5mm plug for the headphones jack) and I use my model 2 (modified with S-Video output) with my CRT. I plan to keep both, and that way I don't have to worry about which model is best.

They both have pros and cons in my book.