>>5684633To be honest, most modern kits are pretty poseable and fun. I say you should just pick one you like the look of and then ask us if it has any problems before you make the final purchase.
Dalong.net has a pretty damn comprehensive gallery to look through, so go find something you like and then come back and ask about it.
If you really want suggestions though, the MG Origin RX-78 (seen here
>>5684605) is stupidly poseable and has very modern and advanced engineering, if you wanted to really be impressed at how far Gundams have come since you last built.
I would also HIGHLY recommend a High Grade from the new Iron Blooded Orphans line. They're marvelously cheap, really fun builds, and the designs are interesting, unique, and very different from each other so there's something for damn near everyone.