What's the differences between Fortinet and SonicWall firewalls ?

Asalam Alycom :) , 

I've already both of them in my company,

Fortinet is stronger than in UTM and has more features not in SonicWall for example :

1) In Fortigate you've unlimited no. of IPsec and SSL VPN users but in SonicWall you've only2 SSL VPN users and IPsec . 

2) Traffic Shaping in Fortigate is an important feature but it isn't in the current SonicWall firmware.

3) Fortinet can be used as a controller for Forti-APs (Access Points) "i.e : there is no need to by an expensive controller for your wifi APs like in Cisco " 

to get good reports in Fortigate you need a FortiAnalyzer Appliance but in SonicWall I think the reports is better .finally I see Fortinet is better in general.

Both firewalls has capabilities of  unified threat management, both firewall has different gui to manage firewall

almost they have the same features, but Fortinet more flexible ( in therm of licensing and renewal ). please let me know if you need more help.