Depends on what you're looking for in a phone.
LG dLite Pros:
Large screen
If you're into Japanese/Korean flip'ish phones this is the closest thing without getting the real thing
Uses microSD card
LG dLite cons:
Just like a Japanese phone you have no access to the web settings menu, so you're stuck with whatever settings the carrier included
Again like a Japanese phone you cannot change the d-pad shortcuts
microSD card is under battery
Camera is located on the bottom of the phone and it sticks out, so it will get scratched unless a cover is used
If you're a male, the phone looks a bit girly
SE TM506 Pros:
Is tetherable if you get and older firmware or unbrand it
Possible to unbrand
SE TM506 Cons:
Uses Proprietary M2 memory
It's a Sony Ericsson, OS has a tendency to hang a lot, you can read it about it in the forums
Build is a lot cheaper compared to a Z750
If I had to choose between these two phones as a phone, I'd probably choose the dLite over the TM150 because it looks cooler. But for functionality I'd probably choose the TM150 because I could debrand it. With that said LG makes the generic Lollipop version of the dLite, which I would assume would overcome the websettings short comings of the dLite. But based on your choice of phones I'm guessing like me you needed the 1700 band, so the Lollipop isn't an option.
If you want further comments on either phone let me know as I've used both phones.
