If a band is playing a Saturday and Sunday in the same town, which is the better night to see them? I would assume Sunday because the band has had a chance to dial in their sound for the venue, but maybe they'd be more high energy on a Saturday.
Depends more on the genre and crowd if you ask me, there's two sides to a performance. On Sunday they'd be less people and those that aren't there don't give a fuck about their job so it would be more intimate but you might not want to mosh with pensioners.
I don't think it's worth worrying about if it's only two nights, it could go either way really.
When I was still an active musician, I did a handful of short tours, and the gigs would be noticeably at their best towards the middle. First night or two was always shaky, but you'd get into your stride after that. Then of course by the tail end the cumulative effects of drinking, sleeping in a van and not having a shower all week would start to catch up with you.
Really couldn't be arsed with all that lark nowadays.