i think it really comes down to what features u really want and whats ur priority in them...
for me i would probably buy the TJ35 over the other clie series for the following reason:
1) SIZE + Weight (Very important)
3) processor speed
granted Clie screen res is important but for a user whose not looking to do extreme stuff with the PDA i dont really see the justifiable need to pay the extra big bucks for hi-res+ screens but thats probably becuz i never had a hi-res+ pda b4 and therefore havent been shown the way to light
anyway i mainly use my pda to read novels, keep contact info/schedules/notes and also play some games when i'm commuting or waiting in line. therefore my main priority is size and weight of the pda becuz i carry my pda in my purse everywhere i go and i dont like to bulk up my purse for no reason. thats why i've always steer far away from the NZ/NX series. the screens are nice but its fatter and its longer and its gonna be harder to carry. i had a co-worker who got one of those and his comment was that he loves it but its harder to carry in his shirt pocket....and if he sticks it in his back pant pocket his afraid he'll sit on it and break it (wonder if anyone ever had that problem)
pricing is also another issue. Looking at the UX50 its a nice sized PDA, but seriously $700 is just way too much to spend on a pda plus given the fact that i'll be upgrading away from it within 1-2 yrs its just wasting too much money
processor speed...well i JUST HATE slow pdas
now...why a TJ35 over TJ25 u might say...theres only 2 added bonus i see but its worthwhile the $40 difference...
1) MP3 Player (it doesnt hurt to have this although i probably wouldnt see myself using it all the time)
2) 32MB Ram vs 16MB Ram (granted majority of us are running alot of programs off memory stick but it really doesnt hurt to have that extra kick)