I think we need to make it a rule to not post threads like this.
No offense intended, really, but there is no definitive answer to this question. And there never will be.
Factors:
Physical location of the phone (for internet speeds, phone calls and gps)
-Internet speed will affect a long list of programs, thus, phyisical location of the phone, affects these programs
Other applications - Windows mobile has THOUSANDS of applications available for it, freeware and paid apps. Everyone will have their apps they use personally, and 99% the list of apps one person uses, will not be exactly the same apps anyone else will be using (factoring in app VERSIONS makes this even more complicated)
-These apps are affected by different roms, usually.
The manner in which you use your phone, is going to be different for each person who owns the same phone.
-You might like to have APP B open while you have APP A running in the background. Someone else might like to only use one app at a time, so speed differences and experiences will vary wildly because of this as well. (open apps use ram, more ram being used, less there is available for new apps being opened.. this can decrease performance)
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I don't feel it neccesary to continue, as I'd assume you get the picture
A good example of what I mean, will show up as this thread gets responses. Meaning there will be different "answers".