In terms of spec, the RG421 will be higher, but they have different neck profiles, so tell him to try them both out at a store if he can. If that's not possible, it's probably safest just to go for the 421 since it's slightly higher end.
^ yeah the 421 is the higher end guitar- unless he has a good reason to go for the other, I'd go with the 421.
I'm an idiot and I accidentally clicked the "Remove all subscriptions" button. If it seems like I'm ignoring you, I'm not, I'm just no longer subscribed to the thread. If you quote me or do the @user thing at me, hopefully it'll notify me through my notifications and I'll get back to you.
Quote by K33nbl4d3
I'll have to put the Classic T models on my to-try list. Shame the finish options there are Anachronism Gold, Nuclear Waste and Aged Clown, because in principle the plaintop is right up my alley.

Quote by K33nbl4d3
Presumably because the CCF (Combined Corksniffing Forces) of MLP and Gibson forums would rise up against them, plunging the land into war.

Quote by T00DEEPBLUE
Et tu, br00tz?
Also, one is fixed bridge while the other is probably using a cheap tremolo. The 421 will probably sound a little better, but if it has the stock pickups it's best to swap in better ones anyway.
Ibanez RG2EX1 Gravity Storm(neck)/X2N(bridge) Drop Db
Ibanez S421 Air Norton(neck)/Super Distortion(bridge) Drop D
7th Heaven->ML-2->Dr. Boogie->Zoom G3->GE-7->NS-2->Mute
Line 6 Spider II HD150+foot pedal
Some 4x12 cab