Vista and FX are both pretty popular here in New Orleans. IMO a lot of the professionally-quality manufacturers are pretty equally matched (they all have their ups and downs). A big part is going to come down to what's available in your area (unless you want to buy online)...
We recommend that professional lighting designers select the correct fixture and lamp for the application not what happens to be available from a given Manufacturer. We will often recommend products from several manufacturers depending on the specifics of the project. Don't limit your product selection to what is locally available either, there are several national outdoor lighting distributors that will assist you to select the right product for your specific application.
Gerry makes a great point above, and one that I agree with and subscribe to. It takes some time to find the best fixture for the application, but in the long run you, your business and your clients will benefit.
Sticking entirely to one line of products is akin to going out an purchasing a toolbox filled with only one manufacturers line of tools. I don't think I have ever seen a toolbox where every thing is from the same brand.
I think that if you go to the AOLP (Association of Outdoor Lighting Professionals) website, you will find a list of very good outdoor lighting manufacturers with products you can depend on. www.aolponline.org