Eldar seem to be getting weaker every time a new codex comes out. Space Wolves nullify their powers with impunity (and don't even get me started on Njal, an upstart who is a better psyker than Eldrad), IG get a fast skimmer just as good as a Wave Serpent and cheaper, Blood Angels also get a fast skimmer. Seer Councils get shut down and other armies can match the speed of mass skimmers. Aspects mostly suck, leaving Dire Avengers as Falcon upgrades to make them scoring and Fire Dragons are suicide squads.
That said, I still love my Eldar. Tyranids are just a fling, Eldar are my first and true Warhammer love. I'm positively giddy over the new Prism and Nightspinner. They are due for a new codex eventually, so here's some ideas I've been kicking around. I haven't really thought these through, so some may be imbalanced and others may not help at all, but that's what the comments are for.
I put my thoughts on some of these, in italics.
1. What if every Farseer's first cast power were unstoppable, but you could nullify the second normally?
This would force you to choose which power is the most important to you, and I hope something like this makes it in. Foolish Mon-keigh should not be able to nullify a Farseer so easily.
2. What if Farseers could use one Warlock power per turn for free (after all they were Warlocks once)?
3. What if the Avatar could join squads and not be picked out, much like the Hive Tyrant in a Guard unit?
4. What if the Avatar could deep strike (and he'd better get fleet)?
5. What if the Phoenix Lords allowed you to take one or two squads of their aspect as Troops (I got this idea from Stelek)?
I really like this idea. It would create so many more interesting possibilities in army builds. We would need Warp Spider and Shining Spear Phoenix Lords, however.
6. Fire Dragons are currently a suicide squad- what if they could shoot out of the rear of a Wave Serpent (and perhaps the Wave Serpent counts as open topped in a turn they do that)?
7. What if Wraithguard kept their gun as is, but with a 24" range?
I really like the idea of Wraithguard, space elf zombie robots, but that short range just kills them, seeing how pathetic they are in close combat.
8. What if Pathfinders were an upgrade character for Rangers, much like and Exarch, that would confer new abilities on the squad? One power could be to allow him to take a shot at any member of a squad. And what if they could fire twice per turn as another power?
9. Swooping Hawks, as they are, don't know what they want. They have anti vehicle grenades and pathetic anti troop guns. What if they could do fly-by bombings like in second edition (with either the Haywire or the Frag grenades), with the number of bombs being dependent on the number of warriors in the squad (perhaps one bomb per two members)?
They used to be able to fly up to 36" and drop bombs anywhere on their path. That was fun.
10. Warp Spiders. How I used to love thee so. What if they got the flame template again?
Old school Warp Spiders were unstoppable with large flame templates and instant death. I would like people to be afraid of them again, not simply mildly annoyed.
11. What if Shining Spears were cheaper and could come in larger squads?
12. What if Vypers could come in squadrons of 5?
13. The biggest problem with Heavy Support is there's just too much competition. To resolve this, what if Falcons could be bought as dedicated transports for certain units, such as Elites?
14. What if the Fire Prism came in squadrons?
I would love this. GW gets to sell more models, and you can take plenty of tanks in the same list. You could even have the Prisms fire individually or charge up for SUPER SAYIN OVER 9000
15. What if the Night Spinner doesn't suck (I would like to see Heavy 2, large blast, barrage, S6 AP 6), and could be bought in squadrons?
16. What if Wraithlords had more attacks and could live without a psychic babysitter?
17. What if Heavy Weapons platforms were bought as attachments to a Guardian squad, like Imperial Guard (and had a drastic improvement in range/power)?
18. What if Dark Reapers had regular missile launchers?
I got into the game because of Maugan Ra. Dark Reapers are my favorite aspect looks wise, and I'd like people to be afraid of them again.