In general, Priority Club is very good for earning points quickly - you will get over 10k points (2k miles if transferred) for your first stay if you sign up for all the 'new member' codes listed in the promo codes thread on FT on the PC board.

You need to think about your travel pattern first, though. Logically, it is pointless earning free flights through BAEC if you can't afford a hotel when you arrive! Points are also generally worth more when kept in hotel programmes - 40,000 Priority Club is 8k BA or a £250 room at the InterCon in Paris, New York, London etc; 25,000 PC is 5k BA or a £150 Crowne Plaza room in a key gateway city.

You also need to think about where you would redeem (assuming you would earn enough). Does a chain have properties in places you plan to go? Do you want 'super luxury' redemptions - Starwood has more top-end properties than the other chains, but then again it is very hard to earn SPG points travelling in Europe. Priority Club has 'cash and points' so as few as 5k points will get you a free room with a co-pay.

Do you have an Amex card with Membership Rewards? You can use MR points to top-off Priority Club, Hilton and Starwood accounts, so those chains become more interesting as you can transfer points to get to the reward you want. These 3 chains also have UK credit cards of their own with a sign-up bonus. Marriott and Hyatt do not have a UK credit card and do not accept Amex MR transfers, so if you are short of points your only option is to buy them at the pricey rates charged.

However, there is also no point in being stuck with a piddling small number of hotel points you can't use. If you are booked into a Hyatt and can't see yourself doing a lot more stays, then take the miles.

Hilton gives you the best of both worlds - points plus airline miles (although you get more points if you choose to ignore the miles).

Note that BMI is far more generous than BA on the hotel programmes they support - Hilton pays out 1,000 miles PER NIGHT (max 3 nights per stay) which on a 3-night stay knocks what you earned on BA into a cocked hat.