First OP congrats on your sweet system - both analog and digital, very well sorted out. I am sure w this level of thought and discernment, you are able to differentiate relative strengths and weaknesses to format. I am fortunate to dabble in all three. I have a heavily modified B77 with outboard tube head amps and EQ.
You have been given good advice. I prefer IEC and 1/4” 15 ips half track. This may limit you but provides a good jump in point. I would recommend a reference tape sampler from Opus 3 to get feet wet. Tape subscriptions can lower costs as does piracy, i don’t want to sidetrack the thread, just give that some thought.
I have heard that stock Otari, i didn’t get the liquid midrange i value so much, but again…it was stock but in a high caliber Ayre and Verity system, no slouch.
You will need to invest in calibration tapes, etc…some DIY expertise. seek out the R2R tapehead sites..no shortage of expertise, opinions…
Best to you on your journey….
Jim