I've taught a few thousand students CPR, FA, AFA and WAFA. Like many have said, I would focus on the practical sessions that are offered to assess different courses. It's not the only criteria, but a great course has to put you through the ringer with a realistic, challenging practical sessions including make-up, scripted actors, wilderness-type supplies, etc.
I was pretty good on single-victim scenarios before taking such a course since my hiking companions had had so many mishaps in the 1970's. But after such a course, I was first on the scene on a multi-car, multi-victim accident and it was easy in comparison. Everyone breathing? Check. Found everyone? Yes. Okay, slow down and go back to the quietest victims and assess to greater depth.
If you end up doing an on-line option for cost or schedule reasons, consider how to get involved in some well-run practical sessions. You could, for instance, volunteer as a victim. It is a valuable perspective on what works well and what doesn't.
I'd prefer a course that had a concise goal: "To provide care for the first 48 hours after an injury or illness" for instance. Or "24 hours" or "7 days". But for the instructor to consciously be somewhere between "treat for 20 minutes until the ambulance arrives" and prep'er-style, "Doctor Quinn, Medicine Woman".
I wasn't as keen on the ski patrol and life guard wannabes who just wanted the cert for a seasonal job. But Boy Scout leaders who would take it that seriously, backpackers who'd seen stuff happen, and especially trans-oceanic sailors were the much better students to be in class with.
Edited to add: ironically, as I type this, my wife is across the room on her computer recert'ing in ACLS (advanced cardiac life support) online. Patient's skin tone, vitals, Q&A, EKGs, response to administered drugs, and co-workers' input are all automated and vary with one's actions and decisions as one gets thrown into different scenarios. Kind of like flight stimulators – they can put you through weird and serious stuff and no one gets hurt. But that's a not a $150 course at the Red Cross!