For what it's worth, piatti, I just ordered and got a BTO iMac 27" 3.4Ghz w/1TB and 256Gb SSD and so far it's fantastic.
I debated between getting that for my coding/graphics work, or getting a new Windows 7 PC. My current Windows 7 PC, mostly used for gaming, still runs things surprisingly well, but is finally starting to show its age. I'll still use that for my hardcore gaming, but the new iMac for everything else.
I also debated getting an all-in-one by HP, Dell, etc., but quickly found through pricing things out that to get one with equivalent features to the iMac would not really save me much money.
And, of course, the question of an imminent new generation of the iMac lineup itself was there.
After a few go-rounds of questioning first one decision then the other I finally decided enough is enough, and made the leap and got an iMac now. (And I didn't want to wait any more because I have all next week off as a "staycation" and wanted to have something by then, so waiting for the next gen iMacs was out)
Could I keep second guessing myself? Sure. The other options I was considering all had a feature/stat/qualities that were desirable, but no one option had enough to feel better than the iMac. And, regardless of what option I had picked, if I kept second-guessing after the fact and doing what-if-this and what-if-that, I'm sure I could make myself dissatisfied with some aspects of my choice.
But, I've chosen to just get on with enjoying the great qualities my new iMac DOES have. I just want to use it and have fun with it rather than keep "looking over my shoulder" to see what I might have/should have done differently. Life's too short!
In any case, I hope you can find something that you can settle down with and have lots of fun using!