Regular basils can get big, but I've been looking for smaller varieties, bred for container gardening, so I can grow them around my deck (and not have to walk far for it! lol) and came up with a couple. For a Thai basil, Siam Queen is compact, yet very productive; though it bolts early, the purple flowers are edible, and taste like the leaves!. And my favorite, for several years, in the Earthbox and hydroponics, is Serrata, a.k.a. Sawtooth basil. It is compact, about a foot high, and a little more in diameter, unless kept well picked - I grow both of these in jr. EBs around my deck, putting 6 in a box - 3 on each side, so more could be done in a regular EB. I have also tried Italian Cameo, but it wasn't as productive as Serrata, and bolted sooner. Last year I tried Dolce Fresca - a Genovese type, which was OK, but not as good as Serrata, and bolted sooner, though all of them grow back if severely trimmed of the flowers. This season, I have another new one - Gecofure - which looks like another Genovese type, and one kudo for it so far is that the seeds sprouted quickly, and it is growing faster than the others I started a week early. I'll keep you posted.
I liked these compact types even before planting in the containers because they weren't tall and leggy, and falling over , like many of the regular types. And they do have a lot of leaves!