Ok first a 65g tank is never going to be "tall" unless it has a 24x12" foot print.
That said, trust me with this, and go with the 65g tank, the 55g tanks are typically super duper thin, they make great display tanks in a fish store, but they make horrible tanks to do anything in, got a 6" wide rock (which isn't very big) whoops, there's half the width of the tank, hope you don't need to clean the glass to well on one of the sides. 36" x 18" x 21" is a decent beginner tank, yeah it's not the longest but you're not going to be putting any tangs in it anyways, and you'll appreciate the front to back depth way more than the 48" length of the 55g.
Although the 65g tanks I don't believe are in the $1/gallon sale. Honestly if the height bugs you go with a 40B tank, they have the same footprint just not as tall, and are really a great ratio of sizes for a smaller/beginner tank.