MacBook Pro Battery Problems
It is common for the Macs battery to stop charging around 93-98%. It does it to prolong the overall life of the battery. Plus, your battery will have some wear and tear now depending on how many charge cycles you have used up.

http://support.apple.com/kb/ht1446#Troubleshooting

But if your MagSafe adapter is charging to 98% consistently and the off brand one is not, then the new cable is a suspect. Charging on Apple devices depend on several factors and there is some intelligence built into the battery IC which I believe communicates with the adapter to tell it when to stop charging. I am not sure if an off brand adapter plays well with the battery IC.