Here's my list. Feel free to shoot holes in it if you like, or, make your case why you think your choice is better in a certain class.
Best buy for a good detector on a limited budget.......Simplex
Best gold nugget machine for extreme depth......GPZ7000
Best overall gold nugget machine........GPX6000
Best dive machine with discrimination.............Excalibur
Best dive machine without discrimination (PI machine)...... Aquascan AQ1B or JW Fishers 8X
Best buy on a PI dive machine......Garrett Sea Hunter
Best machine in iron........XP Deus
Lightest (good) machine......XP Deus
Best overall detector........ Equinox 800. It ranks with the best salt water beach machines, relic machines, Park/school/turf coin-jewelry hunting, and does very well as a nugget hunter too. Very light weight also.
Best overall detector without nugget hunting ........Equinox 600.......also a very good buy
Best pin pointer for land and shallow water..........Garrett AT (now that the White's TRX is no longer made)
Best dive pin pointer......VibraProbe
Best Civil war relic machine......it depends too much on location and conditions for me to pick one "best" machine. Just too many variables.