Either dogface puffer, harlequin tusk or Radiata lion.
Dogface puffer is SO CUTE. It really looks like a dog, sooo personable, and plain amusing. They just look so cute when they look into your eyes as you approach the tank.
Harlequin tusk is from my home country of Australia. Looks full on hectic with the deep blue towards the caudal fin. Has a pretty decent size and it's bright colours really show in good lighting and are extremely vibrant.
Zebra morays... Now were runnin' with the big boys. Sheer size. Great colour. Something different and a real convo starter to visitors who see my aquarium. So lovable and extremely fun to feed.
I don't know if you would count this as an invert, but it is a cephalopod. The blue ring octopus! My friend has a 55gal split into 4 parts, each with a blue ring housed, and a 30gal sump. Such amazing creatures
Not having a quarantine tank is like playing Russian Roulette, nobody wins, you can only see who plays the longest... Unfortunately, I don't have the time, money or patience for a quarantine tank so... That sucks