This isn't a straightforward question, the answer depends on your requirement and your budget.
As a general rule, Chinese engines aren't as good as Japansese or European engines. They are usually mass produced with poor quality components, but having said that there are some Chinese engines which are better than others.
If your generator is going to be under serious load, or it will be run for extended periods of time regularly, or if you depend heavily on your generator for powering medical equipment or something similar, then we recommend you avoid Chinese engines and spend a bit more for a quality engine.
In smaller generators you are looking for a Honda or Yamaha engine - these are without fail the best small/medium engines on the market and whereas they are considerably more expensive, they offer similar value for money given their longevity and reliability.
In medium-sized diesel generators which you might use for powering a mobile home or running a catering van, look for Lombardini or Kohler engines - which are classed as 'small industrial' - as they will run and run without a problem for long periods. Many people look at the price difference between these and Chinese engined alternatives and decide to go for the cheaper option - 9 times out of 10 they regret that decision because the generator they have bought is not designed to run for long periods regularly.
Anything above 8kVA and Chinese engines become rare, as this sectory of the market is dominated by European engine manufacturers such as Perkins, Cummins or Volvo. If you find a big diesel generator with a Chinese generator, think seriously about how you are investing your money - and then buy a European engine.
