I've never had the pleasure of riding in a Taylorcraft so I can't comment on that one, but both the BC-12 and 7 series Champs are great examples of fun little planes.
I would research both planes on the web to find their club sites and ask the guys things like what to look out for with AD's and maintenance issues.
The Aeronca site has lots of info and photos but it's become a ghost town since everyone moved to the National Aeronca Assoc. FB page.
http://www.aeroncapilots.com/
https://www.facebook.com/groups/105851332789460/
There are only a few minor AD's on the Champ, and all of those should have been addressed years ago. The one big one is the wood spar AD, which came out a few years ago. On planes 90 hp and under it's a 1 time inspection, unless there is some kind of wing damage from a ground loop or hitting an obstacle. Over 90 hp is an annual inspection, and the additional inspection after any wing damage like the previous comments.
Other than that, almost all the small light planes have some kind of corrosion issues to inspect for, like lower longerons and such. Most of the planes have been restored and are not stored outside any more so those kinds of problems aren't as prevalent.
Both are fun planes to fly and I would guess that the Taylorcraft would be quite a bit faster than a Champ.
One big issue could be the seating, beyond just a personal preference of sitting side by side or tandem, is your size. Are you a big guy, do you expect to fly with other big guys too, then it could be cramped. These planes were made when people were shorter and a lot skinnier. If planning to fly with your wife, she may want to fly next to you rather than looking at the back of your head. That could be a deciding factor, I would find someone with both planes and at least get a chance to sit in each plane to see what it feels like.
Since you need a starter you'll need to look at something with at least a C-85 engine. I believe that would be something like a 7BCM, 7EC or 7ECA.
Pretty much all of those would have at least the 13 gallon nose tank and at least 1 or 2 wing tanks of at least 5-6 gallons. It may have no nose tank and just the 2 wing tanks of 13 gallons each.
The 7EC has 90 hp and of course a higher gross than the 7AC like my plane, sorry I don't know what that is. The 7ECA has a 100 hp O-235 and the early ones have the oleo gear, square tail and are more Citabria than Aeronca.
As for all of these kinds of planes is the weight issue, which always effects performance. Sometimes people add all kinds of extras like unnecessary instruments, padded side walls and carpet. All of that adds up and sometimes create a real dog of a plane.
My advice, look for one that's simple and light and well taken care of.
Good luck