Dwarfs aren't a recommended octopus for captivity cuz they only grow to a few inches and only live for about 6+ months. Dwarfs are usually sold full grown which are commonly mistaken for baby octopus of a different species. Unfortunate pet buyers get them and the octopus ends up dying in a few weeks because of their full grown life span.
Bimacs are fine. Their actually not a plain species and the best recommended because of their well adapting behavior. If anything, they produce incredible body pattern coloration and are one of the more social octopuses. Grow to about 24 inches across.
If you read the "ceph care" section of this site which every newbie seems to oddly miss/ignore, it has a Bimac Care sheet created by one of the moderators of this site, Nancy. Gives you basically all the info you should need, but if you have anymore specific questions you can ask the forum of course.
The Bimac's origin is on the southern coasts of California and nicknamed the mudflat/2-spot octopus because of their mottled yellowish/brown skin colorations. They have false eyespots under each eye which is one of the biggest distinguishable traits in this species. The truth is, their the best species to keep and good looking at the same time which is a rare case because most animals that are beautiful, are so often not good in captivity like the Mimic Octopus/Zebra Octopus, Blue Ringed Octopus which is lethal to humans, and others. Dwarfs are so much smaller out of the ordinary, and yet they die in only a few months.
A Vulgaris btw...which is the most common octopus in the world and fished commercially every year is another one thats neat to keep, but aren't as easy to get. Their hardly seen on retail sites or sold alive anywere but in Korea/Japanese fish markets. The only thing is that they need a 100+ sized tank because their arms can reach a length of 3 feet.
In one sense, a bimac is a less colorful species. They don't seem to do the rapid color changes that some species display. However, the coloration at rest can be very pretty and they produce nice colors such as purple. I consider them quite attractive. However, bimacs don't produce as much texture as some of the other species.
Marinebio_guy has some baby bimacs now (which he raised) and will have more in the future. He is also an experienced shipper.
Another species for your tank is O. aculeatus, which is seems to be more widely available now than previously.
I am in contact with marinebio_guy and will be receiving one of his baby bimacs on oct 4th he seems very experienced with the bimacs.I will let you know how it gos after i receive he/she and post some pictures he says he has a few left so i would contact him soon!I currently have what i believe to be aculeatus the LFS says it was listed as Bali.I have had him for about a month now and he will only eat frozen foods lol wish they where all like that i have tried offering live shrimp,crabs and live fish and he/she has no intrest in them but as soon as i drop frozen shrimp,crab,fish next to him grabs them right up and eats it.