Opiods will be more addicting, because they make you feel good. Ultram is addicting because it numbs
and calms your senses.
Imitrex doesn't feel addicting, but it affects your mind, and yes, can be addicting to many people.
Again, anything that affects your mood or changes you - can be addicting. Everything from Allergy Pills, to cough syrup, to percocet, to sniffing glue - can be addictive. Just because the research doesnt support it at this time, doesn't rule it out.