My JTM45 arrives this week

Any tips on the best speakers for this please, both as a pair for 2x12 (open or closed, please advise), and a single 12" for my iso cab.
Is it a bright or a dark amp?

At present I have:

For dark or neutral amps:
2x12 for my Fender Twin with very clean Eminence drivers (not sure which model, blue labels)
1x12 Celestion Blue

For bright amps:
2x12 with Eminence Red, White and Blues
1x12 Vintage 30

and my iso cab has:
Celestion Gold
Celestion Classic Lead
Weber Ceramic Blue dog 75 watt with the Pre Rola cone treatment.

I just really want to know what is the sweetest single and double speaker setup, and if any of the speakers I have are a good match

Cheers
Tone

very helpful, thanks

This amp sounds great
I can see why it makes #1 in the Aspen Pittman top 10.
For me it's definitely equal to my favourites.
touch sensitive, with well controlled bass but with a touch of sag, sweet gradual breakup that I can vary with the pick, clear when I want it.
I'm playing it mostly on the strat neck pickup into the top input of the treble channel on about 7 or 8, EQ mostly flat (rolling a little bass off because of the room shape)

I can believe it, I bought a new DSL100 when they first came out, and sold it soon after - great for 80s/90s metal tones, but no feel (and a little too bright for me), and I was no stranger to metal then (at least listening to older metal). However, I must confess, I think I too was guilty of using too much distortion back then

I use a 3mm stubby plectrum (I think I tried it in the late 80s after hearing about Brian May and Rev Gibbons using coins (which I can play with), and although I love listening to fast players, it slowed down my playing nicely), and I can pluck the strings lightly or very hard (typically I have to raise the action a little after it comes back from the guitar tech, since the strings vibrate more and buzz when I play hard).
Please note , it must be 15-20 years since I broke a string, so there's more to it than brute force!

There is a point on the Trainwreck Express that sounds similar, but I had to use a lower-mu tube on the Phase inverter to lose the early fizzy-distortion. Even then, the TWE cam move up to 90s metal further up the dial (especially with a humbucker)

I think they are mostly voiced for Alnicos

So far I prefer either a 1x12 Celestion Gold or a newish Matchless 2x12,
Fane AXA12 was good but not as lively. I have ordered a Wienbrock 1x12 with a Tayden Alnico, and then will compare with these, from memory at the Guitar show, it was closer to the Gold than the others I've mentioned.
I tried them with Vintage30, no good, and my jazz-country-ultraclean Twin 2x12, no joy at all with that. Very poor with dark Fuchs 2x12 (Eminence RWBs)