They all have Pros and Cons... it really depends on the endusers requirement on what they need specifically in the UTM or XTM firewall functionality, and how it is positioned to the end-user as a solution.
I have some documents here, that can distinguish the three send me PM for your contact numbers so we can talk cant place it here...
Firewall Distributor in the philippines
Sonicwall--> MEC Just opened there office this Year
Juniper--> Comstor and Ingram Micro No precense in Cebu only sub distributors
Watchguard --> Lamco with Cebu presence since 1990's
Astaro --> No distributor in Phils, resellers get there supplies in singapore