Russian MFI, page 1

Well, to start out, I was probably wrong about the Pak-fa being based on the Mig, because Sukhoi is the designer.

In early 2002 Sukhoi was chosen as prime contractor for the planned Russian fifth-generation fighter is called the PAK FA

According to Mig, the 1.42 would be able to out perform the F/A-22.

Some stuff on the 1.42 from Global security:

Like the American F-22, the MFI has a thrust vectoring system that allows it to make sharp turns. It also has similar stealth capabilities, with the canard, wing and fuselage structures incorporating carbon-fiber and polymer composite materials. Other stealth features include radar-absorbing covering, screening of radar-visible structure elements, and reduced heat signature. The fifth-generation pulse-doppler radar has a phased-array andtenna with electronic scanning to simultaneously attack over 20 targets. The aircraft can carry long-range air-to-air and air-to-surface guided missiles, and it is armed with a 30-mm cannon.

GlobalSecurity.com

After reading up on it, the Mig 1.42 seems to be the better of the two. It was designed around stealth, where as the Berkut was made "stealthy" but did not have that as it's main objective. Thus, the Mig would hold the advantage in BVR combat, while the Berkut would hold the dogfighting advantage. Assuming this to be true, the Mig is the better aircraft, because it will have teh first opertunity for a kill.

Specifications (taken from globalsecurity.com)

Mig 1.42:

Prime contractor: MiG-MAPO
Nation of origin: Russia
Function: Multi-role fighter
Crew: 1
First Flight: 1999?
In-service year ?
Engine Two Lyulka AL-41F vectored-thrust afterburning turbofans, 39,340 lb thrust each
Wing span: 15 m / 49 ft 3 in
Length: 19 m / 62 ft 4 in
Height: 6 m / 19 ft 8 in
Canard span: 5 m / 16 ft 5 in
Weight (approx.): 33,069 lb empty /
44,092 lb max. take off
Ceiling: N/A
Speed @ altitude: In excess of 2,448 km/h / 1,521 mph
@ supercruise: In excess of 1,224 km/h / 760 mph
Range: N/A
Armament: Unknown but surely any AAMs in Russian arsenal

S-47:

Country of Origin: Russia
Builder: Sukhoi
Role
Similar Aircraft
Wingspan: 15.16 m - 16.7 m
Length overall: 22.2 m - 22.6 m
Height overall: 6.36 m - 6.40 m
Weight empty, equipped : 24,000 kg (52,910 lb) -- 26000 kg (57,320 lb)
Max T-O weight : 34,000 kg (74,960 lb)
Engines: 2 Perm Aviadvigatel D-30F6 (34,170 lbst), or
2 Saturn/Lyul'ka AL-37FU afterburning 142.2 kN (31,966 lb st) with afterburning
thrust-vectoring in pitch -20o to 20o at 30o per second
Max level speed at height : 2,500km/h (1,350 knots)
Max level speed at S/L : 1,400km/h (756 knots)
Service ceiling : 18,000 m (59,050 ft)
Range with max fuel at height : 1,782 nm (3,300 km/2,050 miles)
Number of hardpoints: 14: 2 wingtip, 6-8 underwing, 6-4 conformal underfuselage
Air-to-air : R-77, R-77PD, R-73, K-74
Air-to-surface: X-29T, X-29L, X-59M, X-31P, X-31A, KAB-500, KAB-1500
Crew: 1