Great to know about that implant! I love rats. My males tend to live 3 plus years (just feeder rats), my females live from 1 to 3, but all have developed tumors. I haven't ever been able to find a reliable breeder in my area, but I hear that lines exist that are not so prone to tumors. I've had rats who could be left outside of their cage, and who came when called. Very smart and sweet animals.
Prarie dogs are certainly high on my wishlist, but they require tons of attention, so not a good option when pressed for time. Also, state laws apply.
English lops are the cuddliest breed if rabbit I've ever found, and can be litterbox trained. Neutered males can be especially cuddly and laid back. Some breeds of rabbit are said to lose their tameness if not handled fairly constantly, but that does not seem to be an issue with this breed. Chronic ear infections can be. Caging must be large and care taken so their feet, ears, and extra long tails stay in good shape. Good quality Oxbow timothy hay can be purchased as a fifty pound box for $50 that is delivered to your door (city hay options are limited). I do not recommend feeding rabbits a poor quality hay...GI stasis and other digestive issues are big killers in rabbits. They often do not receive proper diets. Hay bags or racks, or compressed hay is a must if you want to keep a tidy house!! I highly recommend buying from a reputable breeder for rabbits for many reasons.
Guinea pigs can also be great. I loved my tri-roan teddy. He lived for ten years, and was very personable. He pretty much lived under my chin though. X) I tend to meet more skittery guinea pigs than not, and I am unsure how much of that is breed vs. handling.
Lineolated parakeets are a beginner parrot I'm interested in that you might be too.
I tend to like animals with sweet personalities that are open with their affection. Some that appeal to me more for being interesting include tegus, blue-tongued skinks, bearded dragons (though they seem quite endearing too), praying mantises, and various fish.