I restarted the hobby with a betta bowl, then went to a small 2.5G, from there to the Fluval Edge - 1st 6G, then adding a 12G. The Edges are fun, but...
... the most delight I have had so far is with a Fluval Spec! I added a heater in the filter well, and a thermometer. The rest is pretty much the stock tank. I ended up seeding it from my 12G, and it cycled in days! It has plant cuttings from the other tanks. It houses just an Amano shrimp, a Nerite snail, and a cute, bright red betta. Somehow, it is very delightful.
I do water changes with a turkey baster instead of a siphon. I occasionally add Excel Flourish. The sand is natural, no ferts. It does run 80% RO due to the fact, we have softened well water.
The thing is destined for my office, but ounce for ounce, it is an intense delight! I am really tempted to get another one. It is so simple!