In my opinion, I always take the fastest plane I've got. So here is basicly all planes that I take during runs :

Any% :

• 1-4 missions : EF-2000E Typhon II
• 5-11 missions : F-16XF Gyrfalcon
• 12th and 19th missions : RF-12A2 Blackbird II
• 13th mission : R-101 Delphinus I
• 14-15 ; 17-18 and 20-25 missions : F-15 S/MT Eagle+
• 16th mission : R-352 Sepia
• 26-35 missions : Su-43 Berkut

100% (before unlocking XR-900 Geopelia) :

• 1st mission : EF-2000E Typhon II
• 2-4 missions : Mig-33 Fulcrum SS
• 5th mission : F-16XF Gyrfalcon
• 6-11 and 13th missions : R-101 Delphinus 1
• 12th and 19th missions : RF-12A2 Blackbird II
• 14-15 17-18 and 20-23 missions : F-15 S/MT Eagle+
• 24-25 missions : R-102 Delphinus 2
• 26-36 missions : Su-43 Berkut

Why Su-43 Berkut over R-103 Delphinus 3 ? Even if the R-103 is faster than the Su-43, the Su-43 is A LOT more mobile than the R-103 (100 vs 70, source : game or http://acecombat.wikia.com/wiki/Ace_Combat_3:_Electrosphere/Aircraft), which can help you a lot for Tunnel Vision or to chase easier X-49 or UI-4054 Aurora