there are two powerhouses i can warmly recommend but only one of them will be available as choise for you.
First IG Group, biggest retailer, DMA, biggest CFD retailer world wide. Minimum 100 to open an account. Occasionally they serve as market maker for small accounts or unliquid markets, but 95% of trading is done with direkt market acces or through one of market maker/liquidity providers. no conflict of interest. company is big and has a big balance sheet (means the company is stable)
Interactive Brokers, by far the best brokerhouse i've seen, one of the biggest around -probably the biggest- (besides/excluding the Prime Brokers). but they do not target beginners, minimum $25.000 required to open account. not for retailbeginners. They as well act as prime brokers for smaller hedge funds (10m-50m) before these hedge funds manage to gather lucrative conditions with one of the standard prime brokers (goldman, deutsche bank, merryl, etc) They offer maximum leverage of 20 for new clients, if you gain big enough they offer you specialized agreenments to increase your leverage. customers account deposited in seperate holding accounts which are not on the balance sheet of the company, in case of bankruptcy all your money is safe.
in chosing a broker it is fairly easy to see which one is good. the ones who dont need to pay for advertisement and the ones who dont offer any bonuses n top of your initial investment are usually good ones.