I'm throwing in the https://classic.wowhead.com/spell=24894/heart-of-the-wild / https://classic.wowhead.com/spell=17116/natures-swiftness#comments aka "restobear" druid spec (either 0/30/21 or 1/29/21).
You'll be a jack of all trades, master of none, but still viable - depending on your choice of gear - and able to
- farm stuff solo
- do cat DPS in 5 mans (either in damage or in hybrid gear - with hybrid gear you can also off tank and off heal if sh*t hits the fan)
- tank 5 mans and bosses in Alterac Valley (with tanking gear)
- off tank in raids (with tanking gear)
- heal in raids (with healing gear)
- PvP (either as a flag runner, healer or - the most fun - utilizing all druid tools and be a true hybrid)
You could also
- heal in 5 mans, which I avoid as long as there isn't another class with a regular rezz in the group
If you want to excel in a certain role, this spec may not be the right choice, but if you like to be versatile and embrace the life of a true hybrid, this is a great spec and in my opinion second to none.
I played as 0/30/21 for nearly all of Vanilla, and raided as a healer. I quite often topped healing too. I geared HEAVY int, fuck spirit, and had decent mp5. I had over 8k buffed mana in Molten Core and I could just spam Rank 4 HT constantly. It is a very very effective, yet boring, raiding healer. I also saved the raid by being able to shift to bear and OT at the death of a warrior. Battle Rez and Innervate were given to others (I didn't need innervate for myself).
Outside of raids I was pretty viable for PvPing as a feral/resto and also grinding/questing was easy.
8/10 would recommend 0/30/21 druid build for raiding.
For damage, ele shammy and DS/ruin lock are the best. Running the either build in pve loses 5% healing/damage, which is fine for anything but progression. For healing, disc priest and resto druid are nearly identical. You pretty much just don’t have the threat talents. 1% difference, if that. I imagine pallies are the same, but I don’t play ally. Mage and rogue are sort of okay, as are most hybrid specs not mentioned. Everything else, you’re better off just spending an hour to farm the respec gold.
If you have the hit gear, you can DW Fury Warrior pretty well in PvP and PvE without having to change specs. This is pretty gear dependent though. If you're rocking greens and low end blues with low hit, it's going to be miserable.
This was my Feral/Resto build I used back in the day on my druid that allowed me to do my basic resto healing in raids and still have my desired pvp feral stuff for BG's. It made me a beast in WSG. All puns intended. It worked in raids because I was always the raid spot healer. I was never a tank healer.
https://classicdb.ch/?talent#0zL0hZxGMoZVE0oeq
As above, Hunter is good for both, not many needed for raids but you don't need to re-spec, Warlock SL-Nightfall could work for PvE, it's insane for PvP.
Full frost Mage could go too. Fury Warrior is not that bad for PvP, maybe Arms could 5man dungeons and PvP at the same time.