I can't see how anyone could rate Real Madrid's transfer policy as impressive. Firstly, if you're paying the sort of money they are for established world-class players then they should be successful. Signing Ronaldo required zero foresight or insight. That's why they had to break the world transfer record to do it. Same with Bale. They have also paid massive fees for the likes of Kaka and James Rodriguez, who have not really performed for them.
Secondly, although they have done well in the Champions League in recent years, Barcelona have been as successful in the Champions League over the last 10 years or so, while also completely dominating Spanish domestic football.
Thirdly, Real have the advantage of being Real Madrid, which means they can sign almost anyone. So I'm not sure how this equates to an impressive transfer policy. They're getting a pretty easy ride here considering they've finished third in La Liga this season, despite being either the richest or second richest club in the world.
The real test in the transfer market is buying players for small, or relatively small, fees, who then develop into world-class players. I would say over the last ten years that Arsenal have certainly been ahead of anyone in England in this regard. Arsenal sold all of these players for a profit, often a hefty profit having paid virtually nothing for them, in the last ten years or so:
Ashley Cole (Chelsea)
Thierry Henry (Barcelona)
Fabrice Muamba (Birmingham City)
Emmanuel Adebayor (Manchester City)
Kolo Toure (Manchester City)
Cesc Fabregas (Barcelona)
Samir Nasri (Manchester City)
Carlos Vela (Real Sociedad)
Robin van Persie (Manchester United)
Alex Song (Barcelona)
Gael Clichy (Manchester City)
Thomas Vermaelen (Barcelona)
Alex Oxlade-Chamberlain (Liverpool)
Theo Walcott (Everton)
Francis Coquelin (Valencia)
Olivier Giroud (Chelsea)
Kieran Gibbs (West Bromwich Albion)
Wojciech Szczęsny (Juventus)
So an XI of players they've sold for a profit could be something like: Szczęsny; Clichy, Toure, Vermaelen, Cole; Fabregas, Oxlade-Chamberlain, Nasri, Walcott; Henry, van Persie. There are probably other players I'm overlooking as well.
Atletico Madrid would be also be a good call.