This is my experience with slants so far:
iKon X3 (milder)
ATT S1 (mild)
ATT S2 (less mild and more blade sensitive)
Maggard Slant (medium aggressive)
Merkur 37 (aggressive)
German 37 (almost the same as the Merkur)
I use the first three for the most part, along with Rockwell 6S (#4 or #5...