I've played both and liked both. The STLE looked so new and up to date that I feel in love with it immediately. The layout and toys, the lighting and noise (hang on, that rhymes!) all made it feel like it was the one to have.
In comparison the STTNG looked older and clunkier.
However, after a while I realised that the appeal of the STLE started to wear off, and instead of the STTNG looking older and clunkier, it instead looked more solid and respectable, the STLE looked more fragile and an upstart.
The more I played, the more I came to the conclusion that STTNG was the more enjoyable machine.
Don't get me wrong, I still love to have a go on STLE whenever I'm around my friends or see one available to play, because by then, it's a a game that I don't see very often and so it's fun to have a few goes to enjoy that slick look, but it doesn't seem to have the lasting appeal.
Good luck with rebuild. I did mine and it took me some time to get it right. Just stripping the PF to buff and polish it took ages. But the results were well worth it in the end.
I have also done another now for my friend with the STLE who decided that he would have both, although I'm pretty sure which one gets played more now out of the two. No guesses there then.