I would have to say a great white....thats a catch a lifetime..... 
the catch of a life time for me would be a bail.
DIRTY SOUTH SHARK HUNTERS
2012 1st place BLACKTIP CHALLENGE
2011 NO LIMIT TOURNAMENT CHAMPION 2nd year in a row
2010 BHC biggest hammerhead shark on 80 lb test
2010 NO LIMIT TOURNAMENT CHAMPION
2010 BHC 3rd and 5th place biggest shark
2010 april sharker of the month
2009-2010 Rookie of the year
Barry Obama aka The Food Stamp President. Harvested. Not much of a fight at 130 lb though.
1,500 lb Blue Marlin, 1,200 lb Swordfish or 1,000lb Bluefin of spinning gear. Any of those catches would put me in the record books and prove to all I know what I'm doing .
None are realistic however. Realistically at this moment is a fish over 1,000 lbs. if and/once I reach that 1,500lbs and so on.
Anything past 1,500lbs could only be one fish (or a once in a lifetime catch) and sadly you can't catch those any more.
I want a big tiger!
I would love a big hammer or goliath.
Land based grander bluefin