This is always a tough question - however I would pick three - Hamilton, Longines, and GRAND Seiko (not regular Seiko).
Hamilton I believe is THE best option in the 500-1000 range - in terms of quality, variety, history, and quality control (yes - that QC is why Seiko is not on my list, and also I do not like the idea of spending close to a $1k on a 6r movement when an ETA2824 is in a comparable Hammy).
Longines is the best in that 1-2k range - rich history, diverse catalog, quality, and the Heritage Collection is phenomenal (hint hint that giveaway diver would look incredible on my wrist :) )
Now GS is a hot take and probably makes little sense as most of the catalog sits in the 4.5-11k range - but in terms of sheer innovation (spring drive hello), finishing, and craftsmanship (dials are otherworldly), I think that IS bang for buck, albeit in the luxury realm. I was also thinking Omega, but I think the uniqueness of GS makes it a better value overall).
Those would be my top 3 bang-for-buck. Ultimately this is subjective, and in a parallel universe I could have done the same format and said Tissot, Oris, and Omega, but alas - I will stick with the above as my trio.
On a final note, I think each brand irrespective of price can have a relative bang-for-buck piece, and when considering grey or used, sometimes those prices can catapult a watch brand or model into such a designation.
Thanks for the platform and content Max!