[clausok]

re WPF vs winforms: consensus recommendation would be WPF. But for something you're building for yourself, WPF has a lot of complexity that you may not get much benefit from. If you decide on WPF, don't use xaml! Separating dynamic UI into a static markup language is a complexity disaster that will cost you a lot of time. (Note that google results are dominated by xaml answers, so if you want code-only answers it's best to search github.)

Best approach may be a third option, at least as a prototype. Use Excel, with a RTD server that connects to TT. Uninstall the Bloomberg Excel Tools add-in and use direct calls into BBG's own RTD server, i.e., =RTD("BLOOMBERG.RTD","","VGA INDEX", "LAST_PRICE") instead of BDP(...) for market data (~100x faster), and you can get to an 80% solution very quickly.

re F# vs C#, I had used C# for a decade before switching (after I had a vacation ruined because of a multi-threading bug in our position-sizing model. Multi-core parallelism is much easier in F# due to default immutability). If you play around with the F# REPL you'll pretty quickly find out whether the language fits your mind well or not. For me, as soon as I read this code (http://fssnip.net/5I), I knew I had found my native language.