Over 23k Coupons..

VertigoRed

People being mean to honor shop Zanpakuto.... What did Hozukimaru, Suzu(ken)mebachi and Sode do to you.

X-Zero13

If you're a VIP0 (or low VIP that can't afford an event zan), then Sode from honor shop might be a good choice if ur looking for a zan. She's the best F2P zan there is, better than kazeshini in pvp (putting possible zans in ubp aside); I made pretty good experience with her and I am still using her.
That aside, you really should always wait for visored revenge to spend ur coupons and just do as it's already been said here: use only 8k per day (8800 if ur bying the lv 4 stone packs) and go for the 20k reward (since Visored gives some of the spent coupons back, you actually only need to have 16k coupons to get the 20k reward).
In general, spending coupons on stones in the shop is your best option always, because stones NEVER lose their value, unlike gear or partners that you may abandon and change over time. The packs are the most economical way to get stones for coupons; I too recommend you to go for the lv 4 packs for the fury stones, so you can work on your T1 formation (with Urahara, ofc). At some point in the game, T1 becomes standard, so you'd be wise  to go for that too.
Once you have your T1, it wouldn't bee too dumb to go for a specific kind of stone only, if you feel like you need to improve on a certain stat. I once used all the 16k/20k coupons for visored only on strength stones so I could give my Yama some more attack power; during the next visored, I used all the 16k/20k coupons on agi stones to make my urahara go faster.

The best thing in the 20k reward in visored is right now the tier 12 hogu (that's new now, it was only tier 11 before) that comes with like 60 hogu enhancers. Make sure u have a few hogu transformer, so you can change the tier 12 hogu, if ur getting a hogu type u don't need (like stamina. Most preferable would probably be a strength or wisdom hogu, to improve your attack power). Once u have the tier 12 hogu of your choice, spend all the enhancers that visored gave you (and the ones you might already have b4) on it. The difference will be HUGE.