Looking at new rings & base(s) for my .243 Tikka T3 Lite. Considering the Leupold STD or DNZ. What do you recommend?

Neither. I prefer Talley's.

Didn't your T3 come with rings? I have mine installed on my T3 30-06 and have no problem with them at all. I do have an extra set of them in SS. If you're interested send me a pm

I used Lupy rings on my Tikka T3 (didn't care much for the ones that came with it and really didn't want shinny stainless rings)...but only because I couldn't find Warne's at the time. I prefer Warne rings and Warne or EGW bases. That being said, I have a pile of different types of rings, and never had a quality set of rings from any manufacturer fail on me when properly installed.

Yep, when installed properly, I've personally never had a good set of rings fail. Now days, I find myself either using Talleys or Lupy dual dovetails.

My .02 is EGW 20MOA 1913 base with Nightforce lightweight rings.

I have DNZ on my tikka t3 lite 308 and stock on my 243.