Well I only have 100 miles on my new Turner, but so far so good. I did a ton of research when looking for options on new engines and I only found one guy who had a problem with the AB motor and one guy who couldn't get his temps down with his new Turner motor. Even then, both of these issues did not seem to have to do with the engine itself but surrounding systems.

AB and Turner gets 1 year unlimited mile warranty and Turner gives an additional 3 year warranty on the block.

They do not have sleeve or cracking issues due to the way they are constructed.

If you do replace the engine it is important to get the cooling system sorted out. I would replace everything and buy a scan gauge / ultra gauge and make sure the temps are in the correct zone. Currently I got mine down to about 192f while moving and 198f-204f while idle and I am still working on decreasing them a little bit.

I think both AB and Turner engines are going to be pretty good. I went with Turner since a lot of people on the forums say they are they best and even with shipping and not returning the old engine as a core charge, the Turner was only about $300 more.