I'd have to nominate the Top Gun.
http://www.vintagerex.com/pics/gunpics/California PB Supply/Top Gun/topgun.jpg
Made by California Paintball Supply in the late '80s it had a barrel and Q/C held on by spring loaded pins that allowed both to wobble or even drop off in game, a rear pin that blocked the 'sights' and a Q/C that could be unscrewed at the chrono to give a large velocity jump when tightened on field. Add a body made of cottage cheese hardness alloy, a dodgy set of internals and a ropey Q/C and you have an instant classic.
My favourite bit about reading the review in an early UK mag was that after listing all these flaws and more and being rude about it's performance to boot they then went on to say it was all right really
And the Golden Eagle may seem a bit clunky now but when they first came out over here they rocked so hard- you needed big ol' arms to carry one with a 20oz and hopper but the feeling of power was awesome.