Today, on value for money,
TV hands down!
If you're looking for a trackside experience, you can't beat going to the track. The real color, the real speed and if you get in the pit a chance to see the tech stuff up close. You might have two choices for viewing, watching a race from a single vantage point with limited scope or from high in the stands to see more with less detail and sense of presence.
If the track has a layout that allows a good view from the stands you might be able to see more of the race and its flow but little sense of being there. The race, who is fast and who is slow can be grasped better here. It's easy to see a driver falling back or gaining on another. The race comes alive with the use of a stopwatch, using it[them] to compare drivers reveals what doesn't seem obvious at a first view and this is easily done from a good vantage point.
Opting for a spot on the fence, it can be difficult to find a spot to see the action, sure cars might go by but will they be doing anything but parading at that point? There's nothing wrong with being in a crowd with others though. The only real way to see any progress in the race here is by a stopwatch, simply seeing a gap get larger or smaller as a race goes on might do little to indicate who is gaining. I've done this and it can be very difficult.
Maintaining a lap chart is the best way to follow a race, that and the use of stopwatches. Most would not do this but in any long race, any that you might pay to see, it's the way to go.
A race on TV if not viewed live can be seen at your pleasure using a DVR and no standing in line for expensive refreshments. A dry seat is guaranteed and you get to see the races going on that have been picked by the crew that is looking at laptimes and gaps while following a lapchart! The best part, you can see the action, what any of the cars are doing in any of the corners or straights without having been trained to run a 5k race. The downside is that the crew that holds the valuable lap information won't be giving it to you all the time, but usually there's enough given and it would be more than what you would get being at the track.