I've always had a soft spot for the old universes. The necks are just insanely playable, and they still stack up more than well against today's axes!
Having said that, I'd definately look into shechters, they recieve nothing but praise it seems, but overall you may find that if you want a thin neck profile that they may not be for you as theirs tends to be slightly towards the thicker side.
ESP/LTD I can't comment on, and refuse to play ever since they gave mr filth an endorsement despite him not being able to play for ****.
Ibanez: old RG7620's seem to be a firm favorite, I love my old universes, and the s7320 is gaining a lot of good reviews.
To be honest, i reckon your best bet is to go play a few brands to get a feel for the neck.
Then, most likely, have a look at replacing stock pickups.
And finally, this place has a wealth of information and knowledge that's worth sifting through:
http://www.sevenstring.org
Good luck, and ever since picking up 7strings I've always preferred playing them