There's actually already been some lengthy discussion about which stages are good for Ness in the MU thread, the q&a thread, etc, if you'd like to read through it (I understand it's tedious but it saves you the trouble of having to make a whole thread).
Anyway the thread is already here so w/e.
IMO Ness' best stage bar none is Skyworld. It is both high and wide which helps with our survivability, plats to assist with pkt2 landings, enough room in the center of the stage to allow ness to combo freely, and the top plat allows for uthrow -> tech chase. Also things like fthrow off the side plats can really put certain characters in ideal edgeguard positions for us.
I also like GHZ for it's high ceiling (imo Ness kills horizontally more often than vertically) and short walls, which allow for things like early nair/bair/bthrow kills and the plat that moves in the middle can give ness options with pkt2.
Hopefully when people wake up and realize Distant Planet is a good singles stage now it will be in more rulesets because I think it's a pretty good stage for us. Really like the plat layout.
I think FD is pretty good for us.
Skyloft can be okay for us I think as long as we're not fighting someone with a projectile heavy game like Link.
I used to really love Yoshi's Melee but I have friends that main Ganon/Marth so I've really shied away from it.
Not sure how I feel about WW. I kinda lose on that stage a lot unless I'm playing MK.
I hate Dracs. Too big, plat's always interfere.
I hate FoD. Plats always **** up my djcs and Ness has bad mu's with char's that excel on that stage.
I hate Yoshi's Brawl. Huge plat is annoying and the slant in the middle kinda ****s with our pkf game.
I hate Lylat because it's pretty hard to recover on that stage and I don't see how the slant/plat layout helps us.