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 has shown its new-found willingness to spend during 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 season but signaled its 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.

The Reds' archrival Manchester United fared worse last season, finishing seventh, but has shown it means 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 has long dominated the transfer market but has 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 its 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 has brought in Ivan Rakitic, Claudio Bravo, Marc-Andre ter Stegen and, most notably, Luis Suarez as it looks to wrestle back the Liga title.

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

They were both beaten to the punch domestically by Atletico Madrid last season, 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.

Its main rival for the Bundesliga, Borussia Dortmund, also has been busy, signing Ciro Immobile and Adrian Ramos to fill the Lewandowski void, while Matthias Ginter also has arrived to strengthen the defense.

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

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

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