Aspartame is diluted rat poison. The damage it does is gradual and permanent. Kills brain cells, destroys your vision and degrades your central nervous system. Sugar will kill you more slowly and if you can quit sugar the effects (even diabetes) are mostly reversable.
Here's a link to an article that debunks some myths about aspartame. It doesn't directly touch on accusations of "killing brain cells" and "degrading the central nervous system", but it does touch on the link between aspartame and brain tumors.
I used to do a liter everyday of diet Coke or 7up. I'm no Al Gore, but I like to recycle. One day I said "this recycling is just to much bullshit", so I stopped drinking either a year ago. Don't mss it at all.
i used to drink regular coke, then got diagnosed with diabetes, now i drink diet coke, drink way too much of the stuff tho, at least a 6 pack of the 710ml a day, if not more.