The king of all wordpress themes in my experiences has been: Thesis (1.8.5 version)
Strangely enough no one I've seen in my personal circles uses thesis.
They tend to use free themes or some other random theme that can't be customized.
Thesis was the one and only theme that I can endorse (without being an affiliate, obviously) and feel good about recommending to others.
The best gallery plugin that exists right at this moment: Photo Gallery by Envira
It can do simple galleries or whatever you want.
Never take your pictures for granted. If you have ever tried to upload a picture into wordpress directly and it looked weird or wouldn't expand so you could see it properly, you know exactly why this is crucial.
The comment spam plugin: Akismet Anti-Spam
I took it for granted...never!
The comment spam plugin was a god send; whenever I didn't have it, spammers would mess up my comments (those comments don't exist when you use the plugin).
Mobile wp site plugin: WPtouch Mobile Plugin
You don't know how useful this is until people come to your site and leave.
Ever go to a site that wasn't mobile optimized?
You leave almost immediately because it feels really weird doesn't it.
This makes your site look and feel optimized for mobile devices.
These can be put together to make basic stores, complex mega sites, or even just basic blogs.
Thesis isn't free but it lasts forever and I've used it since 2010 to make 80+% of my sites.
The other stuff is more or less common sense that hasn't been so common to many wp site owners.