Their "glory days"?
For us, for sure, I totally approve.
For them...
Let's have a look at the sales' digits:
Kimi no Gin: 60,922
Hikari Furu: 58,379
TTB: 52,413
Magia: 48,679
Oblivious: 38,695
Amongst those you have the three MSMM singles and the debut single, these are kinda "special" in the discography for obvious (I hope?) reasons. And the first Fate single too.
After that, here comes the following:
Believe: 27,722
RYB: 26,244
Sprinter: 23,309
HNS: 20,281
Fairytale: 20,252
Hallelujah: 18,980
HB: 18,704
and 5 other ones below.
Yeah, hopefully, HB is in the lower half of the ranking, but below it you find great ("musically" speaking) singles like Lacrimosa, KSNSNH, or Storia, amongst other.
On a count of 17 singles, Believe and Ring Your Bell managed to rank 6th and 7th. For SME, that's quite a good thing to keep going this way, because the risk is lower than to let Kajiura-sensei experiment, and potentially have to face a commercial failure, like for Storia and its poor 7,093 sales – but yes, I know, that's not an anime tie-in, so let's say: KNSNSNH and its 11,769 sales.