I'd say Begovic is hands down the best keeper in the Prem - he'll get his big move and more recognition this summer.
Next up I'd say Lloris although there have been more and more mistakes creeping into his game this season.
The 3rd one is tricky - form wise Sczezny (sp?) has has his best season and been really consistent Cech is still a brilliant keeper, Howard has been really reliable as ever, Hart has had a tough year but is still a top keeper, De Gea looks great but is often prone to throwing one into his net, like Mingolet - one minute he looks like Peter Schmeical, the next minute he's flapping at a cross, even keepers like Guzan and Foster are top players. It's a shame Krul and Vorm have had injuries as they are top keepers too!
So in conclusion 1. Begovic 2. Lloris 3. Another!