Hmm in my time playing WoW I literally played everything maybe besides BM hunter and Fury Warrior.
I’d say depends if you have any partners to play regularly with or not and depends on what do they play. I play currently with R Druid and Affli so if Ele rework is meh I’m going to switch to SP because he fits other two well. Based on enjoyment level - I like Outlaw Rogue in PvP - the issue is it’s purely arena specs because other two Rogue specs are way better in BGs. Survival is an amazing spec too - a lot of outplay potential and overall unique (it’s not meele as many people think). Devoker is cool as it has unique mechanics to any spec and has quite simple rotation compared to others. If you ask me I’d recommend SP the most probably and if you want to have a challenge go Mage but then reroll completely and focus on all 3 specs. Investing time into Mage is alwasy worth it because no matter what there is at least 1 Mage spec that is good. Most of their mechanics are similar so your learning is always useful. However as I said, Mage and Rogue are the hardest classes to play in WoW so you rather have to main it and invest into it to be really good at it.