Betfair

In simple terms the biggest change is that users can now lay bets and, as individuals with set liabilities are better equipped then bookies to follow strong views, backers can often find better prices on the site.
Trading in odds is also now available where sharp punters can follow the markets, taking big prices about likely movers and getting out, maybe for a free bet with initial stake covered or even a guaranteed profit, as the prices falls.
Well informed, shrewd, disciplined punters can be a traditional layer's nightmare but for Betfair, who pocket the commission whatever the results, it is very much a case of the more the merrier.
For this reason both mainstream and minority sports, where dedicated bettors could well hold the advantage in terms of knowledge and provide problems for bookmakers, are well covered on the site whether football, golf, bandy or floorball is your thing.
A caveat here would have to be that sports which command less general interest offer markets with less liquidity but, while supply and demand will continue to dictate progress in these areas, at least the opportunities are available.
Where the more popular sports are concerned such problems are rarely an issue, especially as far as football and golf are concerned, two section of the site where the range of basics markets and specials are particularly extensive.
Free bet promotions are available and, at the time of writing, a £20 matched deposit, as ever stake non-refundable, can be obtained by new users with the appropriate promotional code which can be easily found on the net.
The site is well designed, simple to navigate and also provides a forum with sections for most major sports allowing users the chance trade views, tips and strategies.
Best-price betting makes long-term profit easier to achieve, so backing/laying at the most generous terms on offer is a must and accounts with the other major exchanges, Betdaq (betdaq.co.uk/com) and Sporting Options (sportingoptions.co.uk), are certainly worth the time it takes to register.
Betfair, however, due to its sheer range of betting opportunities and, most importantly, market liquidity, is the daddy of them all - if you were only allowed one exchange account, this would have to be it.