I have owned a mix of gen, rep and micro brand. I have or have had at least a dozen of each over the past 2 yrs or so ranging from $170 merkur Tuna up to Sinn U1 and a whole lot of reps and micro brand divers in between.
If you are just going for the best spec bang for buck a well known micro brand is going to be hard to beat. Many of these watches can be had for $300-$500 & will come with ETA, Miyota or Seiko movements & have features that a lot of much more expensive watches won't have like ceramic bezel inserts and applied indices. Helm is probably the brand that comes to mind as the best micro bang for the buck. Others worth mentioning are Borealis, Helson, NTH, Scurfa & Obris Morgan
I have had both the Halios puck and the seaforth. Halios watches are really nice, but they are a bit more expensive ($700ish) so I wouldn't say it is among the best bang for buck. There are others that are a bit more expensive like Halios, but are also very well made and rival MUCH more expensive Gens. Brands I world put in this category would be Halios, Helson, Crepas, Aevig & Magrette.
As for reps:
They have gotten much better in the last 5 yrs, but no one is buying reps for the specs. We buy then because they say Rolex, Omega or Breitling or whatever on the dial. I would put the specs off most reps ($300-$500) at the level of approaching the level of the cheapest auto gens or the cheaper good micros.
Gens:
There are some really great gens for the money. There are others too, but the Brand that I am the most familiar with is Seiko & the Seiko divers. The skx007, Turtle, Monster, Tuna, Sumo, 62Mas, Baby Tuna are all Divers that can be had in the $200-$1000 range and all offer excellent value at their prospective price points. If you compare the quality of a $400 Seiko and a $400 rep I would choose the Seiko for quality every time. Then again a Seiko will always say Seiko on the dial and a rep can say Rolex, Omega, Breitling or whatever on the dial