We've spent little over the last 5/6 seasons. oO)
In terms of money though I remember Villa being really inefficient...they spent almost as much as Liverpool over the past 5-6 seasons but never broke the top 4 and look at where they are now. Not to take a shot at them though.
It depends on your definition of "best". 'Arry is the best at wheeling and dealing, for instance.
ManU? They're the biggest club in England with a great manager, and they had unlimited funds for many years as well as a great youth academy that churned out some great players. But look at them, they may not be sustainable, either. They have tons of big shoes to fill: SAF, VDS, Ferdinand, Giggs, Scholes, etc. I don't think their current crop of players, Carrick, Park, Valencia, Berba, O'Shea, the twins, etc. are in the same class. They will have to spend a lot rebuilding the squad, and Ferguson will probably leave right very soon, right when this happens. The next manager will have a hard time I think, and it'll be awhile before they have the success of the previous era.
SAF is obviously also great but I think Wenger is just as good. I don't think anyone could have done what he's done with Arsenal on that budget, and the future is very, very bright for that team. I think they'll be the dominant team in the Prem for the next 5 years, and had they avoided some terrible results (Newcastle, that 0-0 draw with ManCity, the draw with Sunderland, the last minute goals, the CC final loss, etc.) they could have won some trophies this season.