I like MBT for its simple light weight UI for stocks & options, with decent routing (both auto and directed). But with my first need to buy outside the US, explored IB and am now slowly migrating to IB, keeping MBT as a backup.
IB's UI is actually very efficient after 5 mins of using it. In my opinion, I find the order line paradigm muct better than the order ticket paradigm almost everyone else uses. Both are appropriate for "active" small retail traders and neither is appropriate for novice or less-active traders.
Customer service is much more responsive at MBT, though, I am not convinced it is much more knowledgeable. As an example, I note that neither MBT nor IB will, as of this writing, let me route a pre-market ArcaEdge order via their software client. IB admitted to it and claimed their gurus are working to fix it. MBT advertises this capability on its order routing grid posted on its web site, but the software front end won't support it, and their customer service while very responsive insists that it's possible. (He was using an GMS test ticker I confirmed -- I gave up and took him up on his offer to call the trading desk when I need this. On the phone trading desk front, MBT wins.)
The one aspect I haven't yet explored is comparing executions by Knight (the default MM for many OTC orders at IB) vs REDI(Goldman's subsid that is MM for many OTC orders at Penson, the underlying firm for which MBT acts as introducing broker). I've heard good things about both but haven't done a side-by-side.
