Here's a list of the latest poll results: https://realclearpolitics.com/epolls/latest_polls/#
The Senate races matter, but let's not forget the House. Governors would come third, probably.
Also, we should continuously update this list by checking above link every day. I've only included races for the Senate, House, and Governor races (I believe). The other questions are useless and probably biased. One last thing: take these results with a grain of salt: most of them will boost Democrat results right up until the election, then give a more accurate outlook at the end so they can say they were "closest" to the result. The only ones I pay attention to are IBD/TIPP and Rasmussen. On the day of the election, I think LA Times/USC actually had Trump ahead, and were catching a lot of shit for it. Here's an article on them: https://dailycaller.com/2016/11/19/these-pollsters-got-the-election-right-according-to-rcp/
8/23/18
Pennsylvania Senate - Barletta vs. Casey NBC News/Marist Casey 53, Barletta 38 Casey +15
Virginia Senate - Stewart vs. Kaine Roanoke College* Kaine 51, Stewart 34 Kaine +17
Connecticut Senate - Corey vs. Murphy Quinnipiac Murphy 59, Corey 31 Murphy +28
Connecticut Governor - Stefanowski vs. Lamont Quinnipiac Lamont 53, Stefanowski 37 Lamont +16
Pennsylvania Governor - Wagner vs. Wolf NBC News/Marist Wolf 54, Wagner 40 Wolf +14
8/22/18
Wisconsin Senate - Vukmir vs. Baldwin Marquette Baldwin 49, Vukmir 47 Baldwin +2
Florida Senate - Scott vs. Nelson Florida Atlantic University Scott 45, Nelson 39 Scott +6
New Jersey Senate - Hugin vs. Menendez Quinnipiac Menendez 43, Hugin 37 Menendez +6
Minnesota Senate Special Election - Housley vs. Smith Suffolk* Smith 44, Housley 37 Smith +7
Minnesota Senate - Newberger vs. Klobuchar Suffolk* Klobuchar 54, Newberger 34 Klobuchar +20
Texas Senate - Cruz vs. O'Rourke NBC News/Marist Cruz 49, O'Rourke 45 Cruz +4
Minnesota Governor - Johnson vs. Walz Suffolk* Walz 46, Johnson 41 Walz +5
Florida Governor - Republican Primary Florida Atlantic University DeSantis 32, Putnam 31, Nathan 4, White 2, Baldauf 3, Devine 2 DeSantis +1
Florida Governor - Democratic Primary Florida Atlantic University Graham 29, Levine 17, Greene 11, Gillum 11, King 10 Graham +12
Wisconsin Governor - Walker vs. Evers Marquette* Evers 46, Walker 46 Tie
Texas Governor - Abbott vs. Valdez NBC News/Marist Abbott 56, Valdez 37 Abbott +19
Illinois Governor - Rauner vs. Pritzker NBC News/Marist* Pritzker 46, Rauner 30 Pritzker +16
8/21/18
Michigan Senate - James vs. Stabenow Gravis Stabenow 51, James 35 Stabenow +16
Michigan Governor - Schuette vs. Whitmer Gravis Whitmer 52, Schuette 37 Whitmer +15
8/20/18
New Mexico Senate - Rich vs. Heinrich vs. Johnson Emerson Heinrich 39, Johnson 21, Rich 11 Heinrich +18
New Mexico Governor - Pearce vs. Grisham Emerson Grisham 42, Pearce 40 Grisham +2
New Hampshire Governor - Sununu vs. Kelly UNH Sununu 48, Kelly 32 Sununu +16
New Hampshire Governor - Sununu vs. Marchand UNH Sununu 48, Marchand 33 Sununu +15
8/17/18
Wisconsin Governor - Walker vs. Evers PPP (D) Evers 49, Walker 44 Evers +5
8/15/18
Indiana Senate - Braun vs. Donnelly Trafalgar Group (R) Donnelly 51, Braun 39 Donnelly +12
8/14/18
Tennessee Senate - Blackburn vs. Bredesen Gravis Bredesen 44, Blackburn 48 Blackburn +4
Tennessee Governor - Lee vs. Dean Gravis Lee 51, Dean 40 Lee +11
Maryland Governor - Hogan vs. Jealous Gonzales Research Hogan 52, Jealous 36 Hogan +16
New Jersey 3rd District - MacArthur vs. Kim Monmouth Kim 45, MacArthur 44 Kim +1
8/13/18
Minnesota Senate - Newberger vs. Klobuchar Emerson Klobuchar 50, Newberger 26 Klobuchar +24
Missouri Senate - Hawley vs. McCaskill Missouri Scout* Hawley 47, McCaskill 47 Tie
8/9/18
Virginia Senate - Stewart vs. Kaine VCU* Kaine 49, Stewart 26 Kaine +23
8/8/18
Maine Senate - Brakey vs. King Suffolk* King 52, Brakey 25 King +27
Maine Governor - Moody vs. Mills Suffolk* Moody 39, Mills 39 Tie
8/6/18
Rhode Island Governor - Fung vs. Raimondo WPRI/Roger Williams* Raimondo 39, Fung 37 Raimondo +2