My own understanding is that if youre only aiming for loud thuds, you go venus orb.
If youre fine with thuds, then sure, mars.
wat
Atm the only known difference between Mars and Venus is that the latter guarantees at least Thud on the Terminal Coffer.
Everything else like less chances at Mimic, more chances at Loud Thud and blah blah could be real or false but it's just pure speculation at this point.
So what is better between Mars and Venus?
We don't know, simply because we don't know the full extent of the differences between these two types of orbs, other than the one thing I mentioned before which is so far the only demonstrated and known difference.
One small thing I can personally say on the Mars vs Venus matter is "time spent".
When you end up having like, what, over 100 AMAN Silver Vouchers stored up, it's gonna take a long, long time to convert them all into Mars Orbs, with all the constant zone in, zone out etc.
Because of this, someone might prefer Venus Orb in this situation not much for the higher odds at getting loot (we don't know, as I said before) but simply because of the less time spent converting all those vouchers into orbs.