Basically, most of the newer HTC handsets including the Nexus, Incredible, Evo, etc., some of which are available now, others, later this Summer.
The iPhone too, obviously, along with a few months window of the latest Blackberry Bold variation, before it drops to the mid-end due to price cuts.
Aside from the N900, most Nokia phones play in the mid-range. If you wanted to do a side to side comparison of a Nokia phone comparable to a Nexus or the coming Evo, I don't think you could. (**This would also include the availability and quality of applications. A 'mini-computer' as the N900 is called, without a wealth of applications, is a glorified feature phone.)
It's not necessarily a bad thing for Nokia; they're just opting not to spend their resources in the high end area and focusing on middle and lower end stuff. That's a totally legitimate business move. Most of us, including myself, may not like the low end devices, but I bet they sell well in, say, Singapore or the phone shops of Delhi.