found this reference borrowed from Keyhole
Asian 21j
This is one of the most common automatic movements. There are many versions of this movement. Most have proven to be reliable and affordable alternatives to the ETA version. Ticks at 21,600bph.
Asian 7750
This is a chronograph movement that is up for much debate. Has subdials at 12, 9, & 6 that dictate 30 minute counter, running seconds , and12 hours counter respectively. Reliabilityis constantly up for debate, but the general consensus is that if the watch has running seconds at 9, and is well maintained, you will have a replica that will be reliable. The number one rule with an Asian 7750 is to NEVER change the date while the time is between 10 o’clock & 2 o’clock. Also never reset the chronos while they are running. Both actions may cause damage to the movment.
The 7750 with seconds running at 6 is generally the same as the running seconds at 9 version, with an additional module that allows for the seconds to run on the 6 o’clock subdial. This movement is not very reliable, and you should proceed with caution should you decide to purchase a replica with this version.
Swiss 7750
This movement has become very expensive as of late and is not being offered in many replicas anymore due to the price increase. However, this is a great movement and far more reliable than the Asian version. Buy with confidence.
Asian 7753
Similar to the 7750 in that it is an automatic chronograph movement. Subdials are located at 3, 6 & 9. Same issues with reliability.
Asian 2824-2 Copy
A newer movement that has only recently hit the market. This is similar to the 21j, but it beats at the faster and more accurate to gen, 28,000bph.
Manual Wind
ETA 6497-1
This is a handwind movement that is commonly found in Panerai replicas. Another excellent movement.
Asian 6497-1
The ETA versions Asian couterpart. Reliable, but some versions are inaccurate to the genuine. (i.e Missing swan neck). There is an Asian version that contains the swan neck as well.