Which employment-based petition should I submit first?

You are allowed to submit both and have them processed them simultaneously. However, as a Chinese applicant, the waiting time for EB-5 is actually shorter than EB-2. For further analysis, consult an attorney to weigh your options, expenses and requirements.

You may be able to have both pending simultaneously. You should consult an immigration attorney to fully review your U.S. immigration history and goals.

You can have both petitions pending at the same time and they will be processed independently by USCIS. You must choose, however, which one you will use when and if it comes time to apply for lawful permanent residence. It does not matter which petition you submit first. Depending on your country of birth (assuming it is China), the current Visa Bulletin cut-off dates for EB-5 are more recent than the cut-off dates for EB-2, but that could change in the future. Also, keep in mind that an EB-5 based green card will be conditional for two years, while an EB-2 based green card will not.

Both are time-consuming. I would opt for EB-5 as the chances are better for green card acceptance.

The regulations do not limit the number of immigrant petitions that may be filed on behalf of a foreign national. You may file both simultaneously. The waiting period of visa availability is shorter for the EB-5 visa than the EB-2 visa for China.

If your employer filed an EB-2 petition, subject to certain conditions, you can remain in continued H-1B status until your priority date becomes current. You can then adjust to lawful permanent resident status as a seamless process. You are currently in a good position unless your employer would no longer need the position at a later date and before your visa became currently available. Not sure why you would want to file EB-5 if you are the beneficiary of an EB-2 petition. I suggest that you have a good discussion with an immigration attorney.

You can apply for both as both are immigrant-intent immigrant visas. It is best to ensure all is accurately completed absent any errors.

Both are good options. If you can pursue both, you should seriously consider doing both.

You can do both at the same time.

You may apply for both in either order since you are maintaining a nonimmigrant status.