well depends what your after (as everyones already rightly saying). You said you don't want the sunroof because of cost, so from the perspective I'm seeing the LT would be more cost effecient.
Do you value rims (17 vs 15) and leather (leatherette or whatever GMs calling it) over saving a few hundre to athousand (can't recall price diff). Aside from that you can get everything else the LTZ has. The better stereo and cruise control come as the LT connectivity package and I recommend it.
The ride will be equivelant, as others have stated GM had the foresight to offset the diffrent ride characteristics of the rims with dampening changes.
Since your used to use cars either package will be an upgrade, but my vote would be for the LT with 1.4t and "connectivity package". It has everything you need and alil more, your just not paying that extra for status. Its also lighter but that's a moot point for most.
If you have a chance to practice and don't do much stop and go driving the manual is more rewarding and also $1k cheaper than an auto slushbox. If you do try to learn stick the biggest pcs of advice you can get is be smooth releasing the clutch all the way until its fully released (really important on take off, not so much when moving) and shifting at 2k-3k RPM until you get the hang of things. And FYI if you get an auto we won't hassle you
-tyler
P.s. welcome to the forum