That deere looks like a really good deal. I would try and get that one if you can.
If you don't get that one, look for one that has a 52" deck or bigger, a 60" would be ideal though. As far as engines go, kawasaki and kohlers are all good (except for the kohler courage) and the only briggs engine that I like for commercial/heavy use is the Vanguard. I don't care what anyone else says, the vanguard engines are very good engines. On a 52" deck look for a 23hp or bigger engine on it, and on a 60" deck look for a 25hp or bigger engine. Best of luck.
'07 Chevy 2500HD
2010 John Deere Z925A 54" MOD
2011 John Deere Quik Trak 647A
John Deere walkbehind