Lothar
I work with FxPro because of two reasons. First of all FxPro authorised and regulated by the Financial Conduct Authority. Client funds are placed on segregated accounts in investment grade banks such as JP Morgan, Barclays, Credit Suisse etc.
Also they provide negative balance protection, which guarantee a zero account balance and if you fall into negative equity, you can not lose more than your initial deposit. The second reason, I enjoy their platform - Ctrader. It seems very comfortable for me. There are low spreads from 0.2 pips on EUR/USD and FxPro aggregates the best bid and offer across 10 liquidity providers here. There are no limitations on trade sizes, stop and take profit levels.