Kappa Sigma -- The Bolognese heritage (whether viewed as a precurser to or an inspiration for Kappa Sigma) is cool, and the Star and Cresent is a great emblem/badge.
Beta Theta Pi -- This is a fraternity with a Lore like no other I know of; you can't get much better for mascot than a dragon or a guardian spirit's name than "Wooglin"; and you have to give it up for any guys willing to have "delicate shades of pink and blue" for their colors. (The way they connect those colors to the sky at sunrise and sunset, and therefore daily reminders of Beta, is cool, too.)
Beta, Alpha Tau Omega, FIJI, Psi Upsilon, Tau Kappa Epsilon, Sigma Chi, and Pi Beta Phi -- for effective and proper application of the rules of heraldry (including in some cases, separate coats-of-arms for chapters).
Lambda Chi Alpha -- the Cross and Crescent is one of the best, most distinctive, fraternity symbols around.
Sigma Nu and Phi Mu -- Love, Honor and Truth are great ideals. I particularly like the short form of Sigma Nu's creed.
Pi Phi, Kappa Kappa Gamma, Delta Delta Delta, Delta Gamma and Alpha Xi Delta -- the arrow, key, trident, anchor and quill make great, distinctive badges/symbols.
Alpha Chi Omega -- love their musical heritage.
Alpha Delta Pi -- well, they were the first for women, even if others expanded before they did.
And finally...
Kappa Kappa Gamma -- for Ms. MysticCat!
edited to add: Thanks RedRoseSAI, AlphaFrog and KissASinfonian for the nice words about Phi Mu Alpha and Sinfonians!