Welcome back! 9 years is a long break.
The trek from 1- 55-75-85(wherever you plan to take it)will be a bit of a climb on the longstanding servers if you keep to yourself and just solo. There's been some other recent posts with people restarting so you might get ideas there. Definately find a guild that welcomes returning player/low levels --it will make your gameplay way better in my opinion.
If you played EQ back at the beginning and were above level 20, and/or you have been dabbling in other mmo's all along (rather than a 9-year no games situation) then you might like what the Mayong server has to offer:
-On the Mayong Server you will start as a level 51, with good gear and skills/spells ready to go for that level.
-Lots of returning players on Mayong, that only intend to play there. Also lots of test-drive alts and part-time characters from other servers. This basically makes the 51-60 game feel like the 1-25 game did back when I started playing.
-40-50 guilds actively recruiting (way too many imo, but that's another topic). I haven't been alone in Blightfire Moors, Goru'kar Mesa, Blackfeather Roost (all from the Serpent's Spine expansion), Greig's End, Kael (hotzone), Velk's (hotzone), Plane of Justice, Plane of Innovation or Dulak's Harbor yet and I have taken my monk from 51-61 in the past 3-4 weeks. On my old server I would be lucky to run into another person outside of hotzones and some of the TSS zones.
-The economy is new which is interesting. Lots of the oldschool toys are not available, and prices are typically much much lower than I was used to on my old server going back a few years.
-Main downside is 1-50 content is pretty useless, and thats a lot of fun missed for some types of player. I personally have spent the majority of my EQ time delving deep into the 1-50 stuff, so Mayong has been a nice change for me.