It depends whether you mean a team's current home ground or a previous home ground?
So looking at the Premier League - and current home grounds of teams in the Premier league - I've been to 13 out of 20. The ones I've not been to are: Chelsea (Stamford Bridge), Arsenal (Emirates), Man City (City of Manchester stadium), West Ham (Olympic stadium), Southampton (St Mary's), Bournemouth (Dean Court) and Swansea City (Liberty stadium). But if you include the previous home grounds then this changes to 17 out of 20, because I've been previously to Arsenal (Highbury), Man City (Maine Road), Southampton (The Dell), and Swansea City (Vetch Field).
In the Championship I've been to 22 out of 24 of the current home grounds. The ones I miss out on there are Reading (Madjeski stadium) and Brighton (Amex stadium). But if you include previous home grounds then I score 24 out of 24, because I've been to Reading (Elm Park) and Brighton (Goldstone Ground).
In League 1 I've been to 20 out of 24 current home grounds. The ones I miss out on are Fleetwood, Southend, Millwall and Wimbledon. If you include previous home grounds then this changes to 21 out of 24 because I've been to Wimbledon (Plough Lane).
In League 2 I've been to 14 out of 24 current home grounds. I miss out on, Wycombe, Barnet, Colchester, Cambridge, Stevenage, Crawley, Morecambe, Cheltenham, Accrington, and Leyton Orient. If you include previous grounds this changes to 15 out of 24 because I've been to Colchester (Layer Road).
So, that gives a total of 69 out of 92 current grounds and 78 out of 92 if you include previous grounds.
Of course, we've not talked about those teams who were in the professional league but have dropped out since, have we? Teams like Aldershot, Chester, Lincoln, Halifax, Macclesfield, Southport, Torquay, Tranmere, Wrexham and York. I've been to every one of these grounds when they were professional league clubs in the past. So that's another 10 to my total.
Which grounds that I missed out on would I really like to visit? Definitely Arsenal (Emirates) and Man City (City of Manchester stadium). They look like fantastic grounds. I keep threatening to make the short trip over to Manchester and go watch City some day, but the Blades always come first of course.
Which ground that I missed out on am I not bothered about visiting ever? All the ones listed above in League 1 and League 2. Although I'd probably consider going to Cambridge and Cheltenham, because they are nice cities. And I'd probably consider going to Accrington, because it's not too far and I know a lot of good places around there to eat and drink.