XMR is slipping farther and farther down cryptomarketcap.com list.   The price is holding up fine, but not a good sign to have it slide down too far and then it will be irrelevant and people will leave.

Good time to buy do you think?

XMR always seems to get back up to the 0.17 - 0.018 mark eventually.

Darkcoin still shows up, apparently exceptions can be bought.

Buy it 1 more good new and it grow up so fast...

That bug was not only Monero's bug, all cryptonote coins had it until Monero devs got that fixed, and the XMR blockchain was not compromised, you can read the details here:

https://getmonero.org/2017/05/17/disclosure-of-a-major-bug-in-cryptonote-based-currencies.html

And that was just one of the obstacles Monero had to pass in order to survive in past 3 years. XMR path clearly follows BTC path - trustless, open source, community managed and funded, fair distribution PoW - ZEC doesn't have any of those characteristics, its a closed source trusted setup, has corporate management and 20% miner tax.
Monero is a battle hardened veteran with BTC fundamentals with tech that even fixes some BTC issues and has dev team with proven integrity.
ZEC yet has to prove itself when things get tough - do you trust ZEC devs that they won't secretly release more coins or expose your transactions to someone?

This is wrong or at least misleading. That bug, had it been exploited (as it was in some other cryptonote-based coins but not Monero), would been visible on the blockchain.

It is possible in theory that there could be bugs that are not detectable, but this was not one.

Monero is better than Zcash in terms of privacy. Zcash transactions are visible on their blockchain, but in Monero, nobody is able to see your transactions. Monero is 100% private and secret.

Kindly expand on this - how would one be able to identify which coins were "minted" as opposed to legitimately mined on the blockchain?

Because they would have had invalid key images. It's something vaguely analogous to if the amount was -100 instead of 100 but the code had been missing a check for negative numbers. Once the check is added the bogus key images are immediately detected and rejected. Those coins that actually got exploited (BCN, XDN, some others) need to disable the check for older blocks to avoid rejecting them.

Monero was never exploited and doesn't need such an exception.