Depends on what you want. Rebuilding a doormat in a full conference is *very hard*. It’s probably the most challenging thing to do in HD. If that’s what you’re looking for, cool.
If you’re more thinking what will advance you quickly to start racking up Amazon gift cards, I’d say it depends on what you’re qualified for. If you’re qualified for a B- or better Big6 conference program, one that has few or no open scholarships, that’s probably the fastest to *rebuilt* status. If you’re not qualified for Big6 in that world, building a contender from mid majors is very doable. Probably best if it’s not full, but has a few humans to keep overall SOS from crashing. Mid major teams that share a region with a relatively weak power conference are especially appealing, ie if the Big 12 south is half sim, a team like Texas Christian or UT-Arlington can build up quickly.