Gardevoir or Gallade?
Answers
You don't have Gallade yet. You could wait and see if Ralts gets a community day and see if they'll do a dual day, giving Gardevoir and Gallade a revamped Disarming Voice, and Focus Punch, respectively. But right now, both aren't too meta-relevant.
While Gardevoir does all right against Machamp, it crumples against its Steel movesets. It's best fast move isn't effective VS Dragon and Dark, plus it's slow, allowing that Dragonite to smack you with a Hurricane (Even Dragon Tails and Outrages hurt with the immunity) It's far from top option in any raids, outclasses by Dragon, Fighting, and Psychic to take their matchups.
Gallade only has one advantage. It's not weak to Psychic, and its stats are comparable to Machamp. With DP, that would put it just behind Machamp to secure its spot on a chair Hariyama will leave once the rebalance is released. (If ever) It can't learn that though, so it's about as good as Lucario. And on the Psychic side it's dead on arrival thanks to Espeon, Alakazam, Azelf, and Mewtwo. Weighing in these points, I'm going to say that Gardevoir is better.
My advice: Evolve at your own risk!
Both gallade and Lucario cant get DP, gallade cant get Coutner either
revamping disarming voice is...a big stretch, the closest they've done with altering moves is changing power/stats of the moves or the bars on charge moves, there no charge move thats become a fast move. its only hope for a fast fast move would be misty terrain but that as well is a massive stretch, they've only given status moves to pokemon when absolutely necessary for the pokemon (like with magikarp) or theres a specific mainseries link that only a fast move thats a status move can provide (Slaking's truant in the form of Yawn fast 'attack')
Neither. Both at present dont have meta relevance in excess of what other pokemon can do better and in more situations.
Gardevoir is just....no, dont use this thing agaisnt anything other than Double fighting moveset machamp raids or walling the champ in gyms
Gallade's the only real one with potential, given drainpunch and power up punch were found among the list of moves that arent avalable in the game presently but are in its coding, its the only one between the two with any potential if those moves are good enough to compete with machamp, though machamp will still edge out ahead unless the DPS gap is sizable.
Neither have community day potential, given the massive bending of rules it'd take to give gardevoir a fairy fast move and the special evolution requirements that likely would exclude gallade. The two will be like 85% of the other pokemon in the game, so evolve to get your dex filler and continue busting gyms with your machamp and machamp raids with mewtwo/SA Moltres
