the BAM/AMK/AGU are the engines to go for. they all have forged crank, pistons and some form of strengthened block. the rods are not forged although they are the strongest out of all 1.8t engines as I believe they have 20mm wrist pins instead of 19mm like the rest.
one thing the AGU has over the BAM and AMK is the large port head which can be slightly more beneficial when going big turbo.