Mikrotik has been rock solid for me. It's my lack of knowledge really. I adapted someone's QoS configuration and it's been working really well. Much better than anything I've tried before.
My only complaint is the fact is the proprietary nature of Mikrotik. When I was running a small linux box as a router, or when I was running DD-WRT I could always extend the functionality in the ways that's not possible with Mikrotik. The configuration, QoS, everything is Mikrotik specific. I understand that it's reminiscent of enterprise grade hardware though.