The following four albums are Gumi compilation albums featuring various artists:

Boku no Suki-na Bando/My Beloved Band (organised by Hydrangea/bloompot, Yukari is in it!):
https://mega.nz/#!lWwhTaRZ!Hp0aYyHf729yOOUYq-a9X1GxQpzlI6PIpILhnVRWT1o
Pot Pourri 6 (Organized by Nama-Gumin):
https://mega.nz/#!lSpFhYCL!taB7YmR361AuYIRagb25-zdftAUvHdIWHR0UxHjbZ5c
Love Letter Compilation (Organized by Nama-Gumin, CUL is in it!):
https://mega.nz/#!tS5HhayY!svIpEpd-Q72DTL-6y8hC0DSSQJugk37bPvw1LVongpY
Sound Fraternity (organized by kyu-on mama/sound9th, Lily in in it!):
https://mega.nz/#!Ie4x2Qya!sz85AEXECX2dfSFfMDCHtcJj_njaewHKnIehcQW9Snw


cism (they're a rock band who use Yukari Yuzuki a lot):
cism city
https://mega.nz/#!NOhjQASZ!nUYxJRbPRGZzSuOmaiYzjJlFF8vflmclAEqI4hhFWPo
Unlimited Actress:
https://mega.nz/#!sP5jXCBa!UPSyL7GFPitWREH6U1t8Gu5-6n4EAJ5xgQWsPrl3lnU


Yoshi Kai - Megoistic Palette 2 (Yoshi Kai makes anison music, and this particular album does have that late 2000s anime/NND feeling to it):
https://mega.nz/#!sS5Dya5I!cXkXFI8EmwKmmvtJiLNLB5MRAxUAwjsielKhenbvAuA


Ann-Melts P - Rin Len Mania 2 (Ann-Melts P specialises in techno/EDM remixes, and this album also has a lot of rapping from the twins, all the tracks meld into one another, which is why the album has been left as is as one really large file; othe vocaloids including Kaito and Gumi show up to say hi every now and again):
https://mega.nz/#!wXwHwQzC!34A2euJrzuzY3CGiwnNTPLhRfgoKa4N8f9O_38tyX5M


Kayopi (he makes typical Gumi songs - sometimes that's all you need!)
Toy Box Music:
https://mega.nz/#!lTxj3aBT!Y2fJRF9uuRkS7pGZyNvIePftArKKXUjYE0gWrBwlBeA
Spring Garden:
https://mega.nz/#!Ua4lmaJA!IW1kF8WG-8uMemcIuPuEuY2Q6adr1o8sr_ErhTnLTLg
Emotions (a fun album featuring Kizuna Akari about her lover):
https://mega.nz/#!sGwBCKLa!Ma4Wx2fEGqYzGjO7Gb-dB-6Bc3rFkIVlgssFTxBrv2s


Kuni-Ron - Kira-Kira (has maracas, accordions, and a general mediterranian vibe):
https://mega.nz/#!RDgRTSYJ!yr53vbqGSE9Dg69fmc2JHA1GLMxuU3bKwN-bdPzVY5w


Milk Cafe (makes music meant to feel nostalgic and soft):
Essential Milk Cafe (four songs that Milk Cafe feels everyone should at least try):
https://mega.nz/#!BG51QKyJ!OcrhGw4Uo3W57HvVUIkpEIZfZ6mzD18IlFnD2b8aoF4
Parallel World (This is a musical set in an isekai. Featuring a Princess of Music who got imprisoned):
https://mega.nz/#!5WhhjICD!6ql4FFw5emD5Cy6VzJg8WVM9kvD-pbbLTOIAH2q45xQ
Gumi Lover (take a wild guess the contents of this album):
https://mega.nz/#!Mb51zYba!qTREGEs8QWPntzwPk3O5zibIjSM604Rg8d01j8Rncpg


_natural - kanjou-saiseiki/feelings playback device (this album has a kind of a soft rock/jazz jind of vibe. Gumi, Teto, and Kiritan are in it)
https://mega.nz/#!1bhVgA5K!is_WW3sMWUFO7cs6YO03rbP7-4N4M-Sb--94_AHTH5c


Bonus album (no-vocal): 1/6 Gravity by TiNST
https://mega.nz/#!gLoHFQ4I!9CJZQPhkVA160hq3Xq-8j9PnF_45UG9WpndsQs6imvA