If you have a legacy system in place with most of the data - then LSMW is the most preferred route. Check this message -Re: SAP MASTER DATA
Using BDC will be the recommended approach in other scenarios. Please make sure that you are manually able to create a recipe the way you want in the system and design the BDC accordingly (Rules: At least one operation/phase mandatory; PV is created first, etc).
Also, you can explore eCATT scripts - could not find a suitable thread with the detailed steps - but that is an option too.