I have owned the following and rate them :
6500ct/6500 mag -
These are the best for out and out distance with 12 - 15lb line. They can be fully loaded to the lip of the spool without too much problems and the break blocks prevent crack offs. You need to make sure you balance the spools though and they then run brilliantly. They are useless however for winding in anything of any weight ie codlings, rays or doggies.
7ht original -
Easy to cast but very slow running, personally i dont think they are a good distance reel.
525 mag -
Sturdily built but the magnets come loose as do the handles work loose. They are very temperamental for fishing with bait and into the wind. One minute fine the next a birds nest. I find that to get a reasonable amount of control you need the mags on 6-8. They are then quite slow and you can really feel the mags holding the cast back and cutting distance. They also dont seem to like being fully filled and are best with slightly heavier ie 15-25lb line. To me they still need brake blocks to take the initial sting out of the cast with the mags as back up.
Slosh 20 -
These are my favourite for fishing and i keep coming back to them as they rarely let me down when casting decent baits and fishing into the wind. They cast brilliantly with 20lb line and one tiny white block. I can also get away with overfilling the spool and this really adds to the distance. When over filled you also get an extra fast retrieve. Be careful though when cranking in a heavy load as the spools can pop occasionally, its nowt to worry about though. I find that i have extreme confidence with the sloshes and can hit a cast as hard as i like without problems. With a 525mag your just expecting a crack off.The slosh 20 is a superb distance fishing reel but only if you can grip the spool correctly, its therefore best reel down.
Overall if i were to pick reels it would depend on the ground or species i was fishing for.
Clean ground and small fish with 12-15lb line buy an abu 6500 mag
Clean to mixed ground (15-25lb line) buy a 525 mag (but buy the one with extra mags)
All round - Slosh 20 (18-30lb line)
As the sloshes are cheaper you can nearly get 2 for the price of a 525 mag!