I finally playedall 4 Internationanl SRW games and I can say without doubt that in terms of pure enjoyment my list is 30 > X/T > V.
V could have a "better" story and the concept of selecting a real or super upgrade is nice, apart of some units I liked to use like the Xi, Unicorn and 00 QanT Gundams, the Mazinger, the Yamato, the Laevatain and the EVA 13 that sadly for the moment doesn't appear in another game (in the case of Mazinger this specific version that has Iron Cutter and can transform into Zero instead of change to Zero like in X hasn't appeared in other game); the messy traduction just doesn't allow me to enjoy it as much; apart that of the 4 it has the worst gameplay since all the other 3 upgrades its system for better, a lot better.
T is fun, plain and simple, it has the Arcadia, the Bebop gang, the Arhan that I watched the movie just for curiosity and it is indeed a very nice machine, the G Gundam gang (thought it could have been better), GaoGaiGar has the Super AIs unlike in 30, the Gunbuster is awesome as always too and the Black Sarena is more fun than in V; also the OG gang is likeable with all the business motif. My only gripe is that the Support system was extremely underwhelming at that time even if unlike 30 you could carry all your supporters at once.
X can have more problems in their story and is boring that your selections are "Gundam Complex or Wataru Gang", but I can't deny that the series list is very nice for me (please please please put Reconguista in G in a new game please), of the 3 "guest battleships" of the VXT I find N-Nautilus the coolest and also Xelguard is a very damn good unit, its beautiful looking even just standing (thought I agree that it would have been fun having the wings always spread with a morale based transformation). I think I can oversight my biggest gripes just for the fun.
And well, 30 is the peak mechanic wise of what we had before, maybe the free route system can be handled better and the supporters also have plenty space to be better reincorpored but outside that I find it the best in this aspect. The series list is very fine SPECIALLY with the DLCs because how much I love bringing Barbatos and Devolution in my team to obliterate all my enemies; the game singlehandled made me watch 3 new series and I really liked the three of them. My only hope is that the next game is better than 30 well that and maybe put G-Witch alongside IBO, G Gundam and G-Reco in the same title but that's other thing.