i agree with everything @tommor has said above, of course, and i think (hope) his observations will be helpful to you
personally, i don’t think it’s worth obsessing over: most withdrawal difficulties from FCA-regulated brokers are caused directly or indirectly by the customer, not by the brokerage, and in my opinion it’s so difficult to do better than Oanda that it’s not really worth thinking about in any detail
be aware that because of the KYC rules, there can sometimes be a delay with the first withdrawal through no fault of the broker
if you do a search for posts of mine in which i’ve mentioned Oanda by name, you’ll find all my reasons for thinking they’re far better than most, and about as good as you can get
it’s all only personal opinion, obviously