This is the way I'd more likely stack them up.

XTR = dura-ace
XT = ultegra
LX/Deore are next = 105
Alivio/Altus/Acera = Tiagra/Sora/etc.

LX gives you excellent quality and durability for the money. It's not the lightest stuff out there but it is certainly very respectable equipment. The front shifting is not as crisp as XT and the shift lever used to take a longer throw but they may have fixed this. I couldn't make it work with my small hands (I'm 5'3 3/4" and wear women's size 6 with the small hands to match). The front dereailleur used to wear very fast also. If you are used to Ultegra shifting pay attention to the shifting when you go look at bikes. Do a LOT of shifting in the parking lot. As you know, the drivetrain stuff can really impact the cost of the bike but you sure don't want to be retrofitting the bike because you discover you're really, really picky.

Can you rent some bikes first and see what you like?

Sadie "the drivetrain princess" Kate