Ugh, Draytek. Personally I'd use Checkpoint or Cisco - the interface on a Juniper is ick.
Who uses the GUI? The SRX is JUNOS based and that's the best router operating system going, full stop.
I've always been a big fan of the Juniper gear, even the SSG series was top of it's class in most ways despite being slightly encumbered by the sometimes illogical screenOS operating system. The SRX fixes most of the flaws, puts JUNOS in place of screenOS (and as a result moves to a j-web style GUI - it's not bad, certainly better than most firewalls).
There's little not to like about the SRX is the bottom line and that they scale from the SRX100 which is next to no money up to the SRX5800 (fastest firewall in the world according to Juniper) with the same code and same interface is a credit to the platform. The IDP stuff is powerful...
The downside is with options the price starts to increase steadily. For all that though they trash the competition, there's not really anything to compete right now (outside fortigate, who have a promising product but it isn't production ready really yet)
To answer the OPs question though...the config can be a little obscure out of the blocks. If you're using the GUI I'd rate it better than Cisco/Checkpoint/Fortigate but not as simple as Watchguard/Sonicwall (that's because they bear a greater resemblance to SME kit though and simply aren't as good). None are as easy as routers like the Draytek so you'll have to learn a bit.
The only other obvious option is a Cisco ASA which are still irrationally popular with small business. Personally I don't think they're up to much, expensive and limited feature wise, they're the most painful security devices to get interoperating with other hardware and IOS/PIX OS was never a nice CLI for doing firewall stuff (the GUI has improved but is still fairly bad too).