I am debating the exact same thing... Personally I prefer the look of milestone 1 (somehow the 2 just doesn't do anything for me, i absolutely love the cheesiness, i mean the "classic look", of the black and gold combo.. but maybe that'll change), and one of the issues for me is that I don't want to commit to a contract. I can now get the milestone for ~$400 off craigslist/ebay, etc. - the telus contract is just way too long and expensive, especially since I don't plan to get internet on the phone all the time.
On the other hand, the milestone 1's bootloader is still (the last time I checked) locked, so it's questionable whether it will get any future updates, even if you are willing to do the work and flash it yourself. That's kinda annoying. Then again, there's nothing stopping motorola (?) from locking down the milestone 2 as well.
Oh, and if you plan on using AGPS on your phone, I think you have to root your phone in order to get around Telus' gps settings.. just another fyi if you're planning to unlock it, unless of course you're with telus (i'm not, because i prefer to have the ability to go to 2G, but that's probably not important for most people)
So my suggestion to you is that, if you are willing to commit to a 3-year contract with Telus (or could afford to buy the phone when it comes out for $600, $700, or whatever it's gonna cost), then i think waiting for milestone 2 may be a good idea, the milestone 1 will probably look pretty slow (comparatively) and dated by then. Hopefully it won't be too long of a wait - fingers crossed!