Personally I think that this rebuild will take more than a summer, so we're going to finish the summer with gaps and makeweights whatever happens. With that in mind, I think stage one has to be attackers, attackers, attackers.
Klopp had a spell where it was obvious his midfield & attack was on the wane and they needed to rebuild both, but he started by buying Jota, Nunez, Diaz and then later Gakpo and pretty much ignoring midfield. At the time I thought it was odd at a time when they were struggling to even put out a midfield, never mind a title challenging one. But in practice what happened is that their attackers, plus the never ageing Salah, kept them afloat in games where their overall play was poor. That isn't enough to win the league over the course of a season, but it meant that in any given game they always had a boxer's chance.
I would prefer to buy 2 or 3 attackers this summer out of any budget we have, then bolster our midfield with an older player on a short contract. Does that leave us short of quality & quantity in midfield and defence? Sure does, but we're going to be short somewhere, and our inability to score goals is such an awful handicap that I think that has to be our focus. Too many times this season (and for ages before) we've had promising spells in matches, not scored when we're on top, and when the inevitable cheap goal gets given away, we're suddenly facing another defeat.