Personally I would go with the Forgestar, more sizes available and custom offsets. I would go with at least ZCP sizes of 19x9 and 19x10, which the Vossen don't even offer unless you go with 20s. I don't like dubs on a M3...just my .02.
2013 M3 Coupe-MR/BLK ZCP, ACM test pipes, BPM Stg2 dev. tune and Megan catback, AFE Stg2. with C/F elbow VMRV810 19x10&19X11 275/295 Mich PSS.
Previous rides: 2011 M3 Coupe-MR/Blk
2007 Porsche 997C2S Speed Yellow/Blk sport seats
2004 BMW M3 Imola/Blk