It's not too late for HxH... go to suprnova or animesuki... it should have them...
Watch the TV series, then the first OVA, then the second ova (Greed Island), then the third OVA (Greed Island Final)... hopefully there'll be more

As for mecha... here are my recommendations... keep in mind i'm not a huge mecha fan... so if i enjoyed them, you'll probably like them too:

Full Metal Panic! and Full Metal Panic? Fummoufu (or something like that, this is simply comedy... not really a sequel in plot, jut character interactions, still good)

Rahxephon
Blue Gender
Gundam SEED and Wing
Neogenesis Evangelion (either you like it very much or you don't like it at all)
Vision of Escaflowne
Samurai 7 (just started... really a samurai series set in the future... mixes samurai and mecha action)

Comedy, also not an expert, but most comedies are like romance comedy type:

Midori no Hibi (about to end)
Green Green
Love Hina
One Piece (very long action/comedy)
Matantei Loki Ragnarok... (i dont know why but i found it very funny at times)
City Hunter (mokkori!!)
Mahoromatic S1 and S2 (also has some mecha)
Great Teacher Onizuka (A MUST HAVE!!!)
Trigun (action/comedy)
Azumanga Daioh
KareKano
Maburaho
Gash Bell (the first anime to make me laugh just by the first look i got from the character (Gash))
Ping Pong Club
And many many others... just about anything you get your hand on

In reality most animes are not purely comedy, but most of them have many instances of comedy...

If you are also looking for action, drama, sports, weird, or current anime recommendations let us know