middle tier sororities

So I know this is like a lame answer especially because you'll hear it a ton during recruitment, but I wouldn't worry too much about the reputations of the sororities. If there's something really weird about them for you, you'll know during recruitment. If you like the girls in a house though, you should stick with that house regardless of what people say about them.

Most of the mid tier houses actually have great sisterhoods.
From what i've heard Chi O, ZTA, and DZ all have great sisterhoods and when you really think about it that's what matters. Those houses are just examples of mid/low-mid tier houses (other ones have great strengths as well).

I know you've heard this before but DONT LET WHAT ANYONE SAYS ALTER YOUR OPINION DURING RECRUITMENT. If you hear someone say a house sucks and it's a house you like, who gives a crap? Choose whatever house you feel like you've found a home in, after all these are girls that you will be literally eating, sleeping, and breathing with for the next four years. Choose wisely and independently.

AXiDs and Chi Os are going to be your best bet in terms on middle tier and looks/overall. SK and AOPi are bottom houses with good sisterhood. Phi Mu and DZ are a mixed bag of girls, still bottom tier.