What is the best backup solution you will recommend ?

I think it will depend on your infra requirement and what type of service your server run.

One of the company I used to work with have similar mixed environment too, virtualized, Physical and both with Windows and Linux.  For the Windows OS , veeam backup is enough as its host only generic application servers, where veam will automatically create a snapshot backup of our virtual servers periodically. Any bad config changes deletion or failed upgrade etc we just revert back the snapshot via veam or by best practise which is to manually snapshot before any changes. This is also done on generic Linux apache/nginx web server... the beauty of using virtualised infrastructure :)

For physical Linux  files server, we have multiple redundancy firstly through RAID to protect against physical disk crash. We rsync the files to multiple file server beside using custom script to keep multiple version of backups to another dedicated physical.

For database server i have experienced using Tungsten which replicate/cluster our database beside providing Disaster recovery solution. Most database solution like Postgres and Mysql have their built in backup and recovery system too.

I recommend Acronis True Image

Veeam and symantec is the best software for backup

this will vary according to the environment been backed-up , but generally I'd go for EMC Networked or IBM-TSM " now known as spectrum protect "

Symentec is a great way to back up

It will be depended on the infrastructure and the implimentation type, for an organization i'm recommending to use Acronis Backup. Acronis Backup solution is very user friendly and very effective and easy to handle, if the organizatioon have the subscription with google they will have a great amount of storage in Google drive (Depends on the subscription) so the administrators can create auto sync for the individual user profiles and it will help the user to prevent the user data loss during the machine failure or HDD crash and the user can work with their files and access whole their files in any where in the world google services are not banned. 

simpana Commvault and Veeam

Cloud, it could be various...

Veritas Backup Exec and Acronis Advanced Backup with universal license.

EMC Networker Server is the best solution to backup critical business data.