This can depend on a few factors.
The first thing to consider is the use of the instrumental. If you are doing a freestyle, rap or song for Social Media, headed to a party or hosting a rap battle.. The beat store is perfect for you. You might also like the beat store to find inspiration for your next single, you might even find a beat you can just write to and it works. If this is not the case though custom production is probably your best bet. We can do a custom exclusive re-arrangement and/or re-instrumentation of a beat also.
The next thing to keep in mind is how personalized you need the experience to be. The beat store is great for quick, on-demand, high-quality instrumentals. Custom production gives you a chance to write and collaborate with a team. It also includes some coaching and develpoment tips, if you want it.
The last thing I would consider is how exclusive you need the song to be. Even an exclusive license to a beat on the beat store may have sold before. This won't be a problem in most situations. However, if you're interested in having a beat written for you or with you, custom production gives you exclusive rights to the final song.