Best REEL TO REEL blank tape?

Why not try one of each and compare? Also, your deck might've been tuned to record best on particular brand and model. Have you had it aligned and cleaned recently?
I don't know much about R2R but for my Nak I use Maxell Vertex tape which is by far the very best. I did hear that the Maxell tape you mentioned is excellent.
Great project, by the way. I do the same but with cassettes so far. Might get R2R later though.

Some records are very valuable and either virtually irreplaceable or/and very expensive to replace.
Also, I rarely listen to the entire side of a record, I may listen to a track or two so compilations make sense to me.
40 open reel decks, oh man. I would probably have five or so if I could, say, Studer, Nagra, Ampex, Otari, Technics.

Yes, this better/worse/different subject was extensively discussed here. In some ways some recordings can sound better to some ears, mine included. But it takes a well-aligned and tuned great deck with great tape to make this discussion valid, I think.

I am glad this thread is alive, though I don't have any reel to reel deck. Hope to get Otari or Studer one day.
I have Nakamichi 682ZX cassette deck in top condition and use almost exclusively Maxell Metal Vertex backcoated tape. Never had any problems. This tape is the best there is for cassette decks.

Wrong on a few points. First, I have Nakamichi 682ZX cassette deck with custom transformer which is tuned as well as it can be. I also use Purist Audio Neptune top level interconnects with it. It cannot fully match my Nottingham turntable even when using the best tape there is - Maxell Metal Vertex. The deck wouldn’t match top cd player either, I just don’t have one.
Second, It makes a lot of sense to record to tape if you like compilations. I do. I have few records that I listen from first to last cut.
Third. Some of my records are very valuable to me, hard or impossible to replace, so I don’t play them at all, I make recordings.
Besides, good tape on well-maintained deck will last for hundreds or even thousands of plays without deterioration. I have couple of Vertex cassettes with more than 500 plays on them. Records become noisy and wear out, any records no matter how you take care of them.
So, vinyl is great to play but even greater for archive, this is your ’master copy’
Cost for blank tape is reasonable. If you do a lot of recordings at 15ips, yes, quite expensive. For many recordings 7 1/2 two track is sufficient.
Finally, good sound always costs some, and it should.
I record digital too, make compilations. Yeah, sounds a little less digital but not by much.

Now that's expensive. Maxell back coated 10" new was $100 last time I looked. Vertex cassette has exactly the same tape, I think.