Which DLC Store Venue should I look at getting

All of the above.

I personally use the greenhouse items more often as it makes gardening much easier especially if you have seasons in. I rarely use the venue. The tractor is fun for large farming families and for the 'hay ride'. I would put the Bistro at the end of the list. I also use the Brunch items with every one of my saves. I seem to love canning! If I had to pick one to do first it would be the greenhouse. All that glass would make for lovely explosive wounds in your sims. >:)