Suarez, Alexis, Costa? Who has been your signing of the summer so far?

Goal casts an eye over the transfer activity so far in the current window - who do you think has been the shrewdest bit of business?
Clubs across the world are hard at work strengthening their squads as the new season draws ever closer, but which transfer has been the best of the summer so far?

As ever, the Premier League's finest have been in the thick of the action. Arsenal have shown their new-found willingness to spend over the last 12 months and made headlines by bringing Barcelona forward Alexis Sanchez to the club alongside Newcastle's Mathieu Debuchy, who will replace Bacary Sagna at right-back.

Arsene Wenger turned down the chance to raid Barca for Cesc Fabregas, who joined Chelsea instead. Jose Mourinho also brought in two of Atletico Madrid's Liga winners - star striker Diego Costa and left-back Filipe Luis - as he looks to launch an assault on the Premier League title.

Liverpool narrowly missed out on the crown last term but signalled their intent to remain at the top end of the table by signing Southampton's England duo Adam Lallana and Rickie Lambert alongside Bayer Leverkusen starlet Emre Can.

Their arch rivals Manchester United fared all together worse last season, finishing seventh, but have shown that they mean business under new coach Louis van Gaal by bringing Luke Shaw and Ander Herrera to the club.

Manchester City won the title last time out and have long dominated the transfer market but have had a decidedly more quiet summer this year, sealing a bosman deal for Sagna, completing a long-awaited move for Porto's Fernando and signing Willy Caballero to strengthen their goalkeeping options.

Real Madrid and Barcelona have long been locked in battle both on and off the pitch and have both been big spenders in recent years. This summer, Barca have brought in Ivan Rakitic, Claudio Bravo, Marc-Andre ter Stegen and, most notably, Luis Suarez as they look to wrestle back the Liga title.

In contrast, Madrid have been slightly quieter, only signing Toni Kroos from Bayern Munich, but are expected to do more business in the coming months.

They were both beaten to the punch domestically by Atletico Madrid last term and Diego Simeone's most notable bit of business so far has been the acquisition of Mario Mandzukic to replace the outgoing Costa.

Mandzukic left Bayern Munich primarily because of the signing of Robert Lewandowski and the Pole is one of three arrivals at the Allianz Arena this summer, alongside Sebastian Rode and Juan Bernat.

Their main rivals for the Bundesliga, Borussia Dortmund, have also been busy, signing Ciro Immobile and Adrian Ramos to fill the Lewandowski void, while Matthias Ginter has also arrived to strengthen their defence.

Immobile was partially owned by Juventus, who have had a frustrating transfer market, but the signing of Alvaro Morata has lifted the spirits of the Turin side.

AC Milan, meanwhile, have brought in Jeremy Menez and Alex from Paris Saint-Germain as they look to regain a top-four place under Pippo Inzaghi next time out.

PSG themselves have also had a quiet summer by their big-spending standards, with their only major signing coming in the form of David Luiz from Chelsea.