A pair of enlargers for your largest format is the bee's knees. Smaller enlargers seem more convenient, but the bigger ones are more stable. There are always the trade offs of space, weight, cost, etc. If you have a portable darkroom, a floor standing 8x10 enlarger is not going to work well. In my bathroom/darkroom I have to be able to lift the enlarger onto the sink counter, also I have to be able to walk between it and the toilet, those are kind of real limitations.
Of course if you have a large dedicated darkroom, you do not have those limitations. You may, however, have a height limitation. You also run into tradeoffs of how large a print you can do, it takes a lot of space to do large prints.
On the other hand, if you are working entirely by yourself, having to expose the paper, develop it, hang it to dry, then start another, there really is no need for more than one enlarger. When you are just doing the printing; and handing off the processing to someone else, or a daylight feed processing machine, then having more than one enlarger will increase your throughput quite a lot.