It depends, I suppose. The original japanese VA Marth sounds great, whether young (Smash), or older (newer FE games). Yet Yuri does a wonderful job. It was difficult to hear the attack and pain/take-hit noises Yuri made with him with the background noise or commentary filtering that out in gameplay videos (they don't seem distracting at least), so how those sound will be important. And the "Keep your eyes open" on down-taunt will be the trolliest taunt since "You're too slow" from Brawl! Just think of the possibilities.
The last thing is Counter Quotes. They weren't in Smash 4 and we didn't hear them in SSBU and I don't think they'll be in (they already had the voice actors come in and that's it, unless they had Yuri record some just in case). I really want CQs and I truly don't understand why they're not in when most of the other characters have counter quotes.