Speaking from experience, the AMX-30 Super is very good. I don’t know about the VBCI since I don’t own it, but 30mm Bushmaster vehicles usually aren’t great. The CV9035NL is decent.
Just keep in mind that the AMX-30 Super can only grind through Rank VII, and the CV9035NL can only grind vehicles Rank VI above.
It really just depends on what BR you are for France. I would say that unless you are at or very close to Rank VI, buy the Somua SM. The Somua SM however is a heavy tank and heavy tanks are the worst kind of premium to buy, although the Somua itself is pretty decent. It really suffers in uptiers.
i don’t play arcade but for sure vbci is not great, it is a special gameplay and hardly work most of the time, amx 30 super is clearly a good option to grind the tree, somua sm is really great with his lineup at 7.7 especially to print sl but you can’t uptier him much.