I've done a little work with Moto's, mostly the C650 and moto triplet range. (V220,300,400,500,etc etc)
I'd rate them as pretty run-of-the-mill phones, average performance, fairly good implementations - I've had no need to go looking for the developer site.
Some of the SE phone are abit expensive, though the K500 is meant to be rectifying this.
Its basically a stripped down K700, no bluetooth, only 12mb ram instead of 30mb, slightly smaller resolution.
I think you can get it for around £100 on pay as you go, or for free on most contracts.
Its got it where it counts though, midp2, cldc1.1, JSR184(m3g), Mascot Capsule, 1.5mb heap, and its a pretty fast phone too. (infact, due to the smaller screensize, and newer firmware the K500 is a good deal quicker than the K700