welcome aboard *passes the rum*
eh, it's a rather difficult question, matey.
You are basically asking "what to download", right? Hmmm a balance between pretty stuff x low poly is rare, and, depending on your taste, you make have to give up on certain CC (...or wait more 50 secs for the game to load).
Some stuff I advise you NOT TO HAVE
ElvaSims stuff: Yeah. It's pretty, nice and fancy. But the high poly stuff makes the game SO LAGGY. Sad, indeed.
Dincer Stuff: Expensive and High Poly. Avoid.
Butah stuff: Low poly, but at the time you clogged your downloads folder with her crap, you already got burnt retinas JUST FROM THE PREVIEW PICTURES. Have some self-respect, please.
Low Poly Creators
That's a list I'm slowly building myself.
I have found that boblishman from MTS2 has some cute low poly objects
www.ogularama.com is very cute, too! I love their stuff. Plus it's also low poly.
I'm new at this whole "poly watch" thing, too. So, suggestions/tips shared are HEARTED.
When I finish scanning my DL folder I shall give more pointers.