which era had the highest ratio of crooked top level fights?

Yes. But top level fights ?
In hindsight the era was arguably the 'golden age' of boxing, and also the early televised era.
Then - as now - fans and fighters complained a bit about bad or crooked decisions, certain fighters being 'protected'. That's a constant in all eras.
But fans and press were probably also way more vigilant regarding dodgy stoppages (LaMotta-Fox for example) and any time a fighter quit on his stool questions were raised. Boxing commissions often suspended fighters who took the easy way out, or fell down from light punches. These days I think we as fans are far more tolerant.

I just see too many good top level fights and fighters from that (1945 - '55) era to consider it the most crooked. Boxing seems to be more 'fake' now, if I'm honest about it.

 

Yeah, I think the early days sport were the worst.
Like the 1890s and 1900s ... and before.
When the fights were illegal, and everyone carried six-shooters.