Another vote for P-Line X-Strong. I tried a 12lb on a levelwind and although incredibly strong, the memory was the worst I had ever seen in any line. On a centerpin, that of course wouldn't be such an issue.
Another highly regarded line is Ande, which I tried this past season in 16lb (also on a levelwind). Pros: fairly limp, pretty tough (abrasion resistant), cheap, all-around solid reviews from its users. Cons: consistently got beat by a 10lb Maxima UG leader, after only two outings it started losing color (getting pale/dry) much like Maxima UG, have to order online and smallest size is 1/4lb spool (around 600+yds in 16lb).
This year I'll be trying P-Line CX Premium in 25lb. I was gonna go for 20lb, which would have had a diameter slightly thicker than a 12lb Ultra Green; 25lb would be equivalent to roughly a 17lb UG (if it existed). I'll do a review on it later in the season.