I'm now up to episode 6 of Spielban. It took a little bit to find its footing but I am pretty invested with this series so far.

What are considered the best subs for OG Garo?

If you can't track down the blu-rays, your best bet is probably the GomenRider version. They're just a scrub of TV-Nihon, but the video quality at least should be better. I don't think Over-Time ever went back to do the original series.

Noted. Thanks!

No problem. Honestly not sure I'd even recommend the blu-rays. High definition does not play well with Garo's 2005-era CGI.

I'm now up to episode 15 of Spielban and I'm really liking the series so far and Machiko Soga did a great job as Pandora.

Agree. Further it will be even more interesting.

I'm now up to episode 30 of Spielban and I should be able to finish that series in the near future. While I am planning to watch Jiban next, Metal Heroes-wise, I'm honestly tempted to watch Shaider afterwards instead just so I can officially say I have seen all three shows that were used as source material for VR Troopers like I have with two of the three 90's Kamen Rider movies (ZO and J respectively) plus Black RX since they were the source material for Saban's Masked Rider.

Not exactly tokusatsu, but I think many will be interested. The fact is that the first film about giant (more precisely, just large) robots was shot in the Soviet Union in 1935. It's called "The Death of a Sensation" or "Jimm Ripple's Robot". Poster:
https://i.ytimg.com/vi/1PhhcdykZKw/hqdefault.jpg
But for a better understanding, it is better to look at the excerpt:
https://www.youtube.com/watch?v=-IdLBGM1pa0

I have just finished Spielban and it is another Toku series I can officially cross off on my own watch list. While Metalder still remains my overall favorite Metal Heroes series so far, Spielban, at least for now, is a pretty close second.