Make sure its a heavy duty trailer. If you go 20 ft watch out for the ones that will flex when loading and unloading. I bought one that was to light and the frame cracked all over. Now Im shortening it to 18ft and having it rebuilt. Thats all I need for 2 ztrs and 2 walk behinds and a basket up front. 20 ft also makes it hard to park between driveways in some areas. Get what you need don't go bigger than you need.
2013 Exmark Pioneer S 60" Ultracut (Review with pics) http://www.lawnsite.com/showthread.php?t=410996
2010 Badboy Outlaw 6100 31 KAWI
2008 Exmark Lazer Z AS 60" U/C 28 Kawi
2000 Exmark Lazer Z 60" L/C Kawi 4100 + hrs strong