The answer to this is dependent on you as the patient. In general , based on molecular science known about the brain receptor to CBD and THC, I tell patients that getting CBD only products is probably not as helpful as getting something with at least some THC (it’s called the "entourage effect"). All the different products have different advantages/ disadvantages. Vape-pens are good for more-immediate pain relief but they don’t last as long ; if you are having issues with sleep as well, a micro-dosed edible is probably more useful but be prepared to wait 45 min – 1 hr plus. Topicals may also work for many but not all patients (better used if area is pre-treated with mild heat, something you should be doing for your back anyways). Back pain is never treated in a vacuum in my practice so I always remind pts to look into additional modalities including but not limited to: stretching, yoga &/or tai-chi, frequent use of heat/cold application to back, weight loss (if applicable), physical therapy &/or massage &/or accupuncture &/or chiropractic, a home electro-stimulation/ TENS unit. I hope that all these suggestions help for your back pain issues.