From my experience of using both (we've got some backup systems using Backup Exec, and some using NTBackup), I would prefer to go with Backup Exec if I had the choice.
I've never actually tried using NTBackup to backup a remote machine, so I can't really comment on that, but I was under the impression that it couldn't handle it, however I could be wrong, I'm also unsure how it handles backing up Exchange.
What I do know is that NTBackup does indeed work, and it does do the job it is designed for, however the problems come when things don't work.
Firstly, on the one occasion that I did have to do a restore from NTBackup, it was an absolute nightmare. I had lots of problems getting it to recognise and catalogue the information in the backup so I could run the restore. It did eventually work, but took a lot longer then it would have taken with BEWS.
Secondly, if you were planning to backup the remote server locally, and then move the backup file to the other machine to be backed up, I should point out that for some reason, NTBackups .bkf files don't like being moved around a network. I don't know why, but it is a known problem. I found myself in a situation once where I had to find a utility on the net to allow me to access the .bkf file directly, and restore the required files from it by hand. A challenging, though not overly enjoyable experience.
Thirdly, once you have done a backup, you obviously want to be able to confirm that it has worked successfully. NTBackups reporting features are extremely limited at best, making it difficult to find out if the backup has been successful, and if not what caused the problem. Compare this to Backup Execs easily readable output, and over time the extra time you end up spending checking the information might make the price saving you make irrelevant.
Finally, you don't have any of the reporting information relating to tape usage, soft and hard errors etc with NTBackup, which can be very useful when you trying to diagnose the cause of a failure.
I hope that helps.