Well, my honest opinion: Buy it. Don’t think about it, just do it. Once you use it for a week or so and learn its conventions, you’ll never look back. I’ve been using LW since it’s first beta; I still use it everyday, but all of my modeling is now done in Modo.
LW & Modo play well together…go figure. 
Silo is a great & powerful app, but I’ve never really liked the workflow methodologies.
Wings3D is also good, and cheap.
But like Silo, it just didn’t work for me from a logic standpoing.
In Modo, I feel right at home. It allows me to work the way “I” work, and for me that’s all that matters. 
Unfortunately, Modo doesn’t yet have a trial version, or I’d say download them and try all three to see which one works for you. These aren’t the only apps on the market obviously, but they all 3 quite versatile modelers.
All that being said; Just get Modo, you’ll love it. 
