I would think the hosted singles cruise, the prices are more to pay for more activities and the hosts way. Are you wanting to meet someone or just cruise? Once you decide that question, you know if the higher price is worth it or not.
I cruise solo and there are always people to talk to. Carnival will seat you with other singles, sisters, friends travelling together if you request traditional dining.
One thing about cruising solo, Im not doing the activities someone else wants to do, Im doing the ones I want to do when I want to. I can turn on the tv in my cabin and not worry what my roommate will say. Cruising solo is fun even for regular cruises. I saw Tulum solo and just join up with a cruiseline excursion and seem to meet other solos to sit with on the bus.