Are all encryption tools made equal? I'd like to encrypt work-related data backups stored on an external drive. The backups contain proprietary company information and trade secrets.
My current backup program, Comodo Backup, allows me to encrypt backup files with AES, Serpent, XOR, and other schemes. However, I've read about vulnerabilities in encryption tools (such as TrueCrypt failing an audit by Google's Project Zero team).
It would be more convenient for me to let CB create encrypted containers, but if necessary, I can have it make uncompressed/unencrypted backups, then encrypt them manually after the fact. Thanks for your help - obviously, my knowledge of security and cryptography is very limited.
Here is the only information I can find regarding their encryption method:

Encryption Algorithms:
3DES - 168-bit/ strong
AES - 128bit / strongest
Blowfish - 64-bit block / strong
DES
Serpent - 128,192 or 256 bit / very strong
Twofish - 128-bit block/ strong
Xor - Variable block size / weak
CBU generates a 32 byte key by applying a SHA256 hash algorithm to the password entered by you. If the encryption algorithm chosen by you requires a key of smaller bit length, the 32 byte key is truncated to the required length. CBU encrypts the backup file with the chosen algorithm using this key. During the restoration the backup file, CBU receives the password entered by you, generates a key by applying the same hash algorithm and uses this key to decrypt the backup file. If a wrong password is entered by someone maliciously, the key required to decrypt the backup could not be generated and the backup could not be restored, ensuring additional level of safety to the backup of your confidential information.

Rather than rely on Comodo Backup to handle the archive encryption, should I use a more specialized tool such as VeraCrypt?
No, not all encryption tools are made equal.

Even when using the same cryptosystem, say AES-256, a tool's choice of cipher mode, how to generate AAD if present, how to generate IV, how to generate key, and the quality of the random source all affect quality.  The quality of cryptography engineering is the major deciding factor at that point and it is tricky to get right.

To determine if you should use VeraCrypt or let Comodo Backup do the encryption you need to assess the effectiveness of their cryptography engineering.

The simplicity of using the built-in encryption supplied by Comodo Backup is a significant convenience advantage.  If their crypto eng is up to scratch I'd make that your choice.