I'm trying to make up my mind and choose a broker, however much of my choice depends on the trading API offered. I'm definitely not interested in FIX solutions and I'd very much like a .NET implementation of the client interface.
So far I've looked at MBTrading (poorly implemented, not compatible with modern software stacks), IB (complicated, not .NET, requires their TWS software to be running as a proxy), Thinkorswim (little documentation, not .NET).
I also have some experience with Lime Brokerage's API, which is very nice indeed, however I'm afraid the operation I intend on starting might not meet their minimums.
Are there any good alternatives?
Of course an API is worthless without an efficient broker, so speed of execution and a decent fee structure would be appreciated.
Thanks in advance.