Thread Title: Looking for reliable brokers/platforms for trading plain vanilla options with real-time margin updates

[ThetaShark]

Hi everyone,
I'm looking for advice or feedback on which brokers and platforms are considered the most reliable for trading plain vanilla options on official exchanges (e.g., Eurex, CME, CBOE, ICE Futures Europe/U.S.).
Specifically, I'm interested in brokers that:

• Offer efficient margin management for multi-leg strategies (spreads, straddles, condors, etc.)
• Provide real-time margin updates as the market moves
• Are transparent in how margins are calculated
• Support access to both US and European exchanges (including ICE Futures Europe)
• Offer a robust and stable trading platform, suitable for professional or high-frequency options trading
• Ideally, also provide dedicated operational support (not just standard customer service)
• Bonus: availability of a paid desk or advisory service for urgent or complex operational issues (e.g., desk access via phone/chat/email during market hours)

If anyone has experience with such brokers — either from the UK, EU or internationally — I’d really appreciate your insights.

Thanks in advance!