What kind of budget are you working with, are you looking new or used? I was looking for a tandem small enough I could handle it solo or with my kids, who are young enough they can’t really help paddle yet (5 and 3).
After a lot of research I purchased a used royalex Bell Drifter (actually rebranded as a Galyan’s Woodsman III), and it has served my needs well. I put a kneeling thwart in it, and I canoe from that position when solo or with the kids in the canoe (solo, but heavier). It’s 15’6" with decent rocker, so I can maneuver it pretty well down wide rivers and slower creeks, but it’s 36" wide with no tumblehome, making reaching the water with the paddle difficult without healing the boat some. I would really want a narrower boat to go down technical water or faster streams. (Bell made that canoe and rebranded them for Galyan’s, with some woodsman III’s being a no tumblehome 15’6" drifter and some being a 16’6" shouldered tumblehome Northwind hull. I’ve seen both on Craigslist recently, so you have to pay attention to which hull it is). Bell also made some Drifters and branded them for Scheel’s as well.
The Bell Drifter hull is the same as a Bell Morningstar, but the Morningstar has a shouldered tumblehome, so a Morningstar would handle the same, but should be a little easier to solo from a middle seat or kneeling thwart. Bell also made a Yellowstone tandem that would be a short tandem you could set up to solo, but it’s a more rockered hull that probably wouldn’t serve you as well on lakes and ponds. I’ve seen a lot of people mention the Old Towne Penobscot 16 as a lightly rockered tandem that can work as a solo. The royalex version of that boat would be lighter and easier to manage solo, but harder to find used. Wenonah makes the Solo Plus as a tandem/solo boat. There are a few companies that make prospector canoes in 15’ or 16’ models, those could be worth looking into as well.
The problem I have is that the more time I solo my boat, the more I want a dedicated solo. I can really battle the wind some days paddling by myself, and a little more maneuverability would be nice. As a tandem, my boat works well, but I don’t have the capacity or efficiency of a longer boat.