There's a progression. If you've never had a computer on your bike, it's a lot of fun to put one on, and look at the numbers while you ride. After you've had that for a while, and the battery dies or the wire gets snafu, the screen goes blank; and after a while you stop looking at it. At this point you start seeing all kinds of stuff around you. And it's great fun to take the computer off your bike and forget about it.
As for wireless computers, they pick up on random signals. I've recorded top speeds well over 100 mph. This screws up everything.
I use Strava and similar aps on an android tablet. These screw up data too, but I like having a map of where I've been.
Well, that's one progression. Another is that after the batteries die in your first computer, you realize how much you enjoyed tracking your progress as a cyclist, and want to take it to the next level. For me, that next level was GPS tracking. GPS tracking has transformed the way I plan my rides. It allows me to retroactively look at the routes I rode and decide which parts of those to incorporate into novel routes. Before GPS, I would have a vague idea of where that great fire road shortcut through the woods was, but it might be so remote that it's not even on an old-school map.
Sure, Strava and other tracking apps exist for smartphones and tablets, and I use Strava for shorter rides, but smartphones and tablets generally aren't sustainable for all-day rides, as GPS kills battery life (my iPhone 5 will get me five hours tops with GPS on). Better to have a dedicated yet inexpensive GPS-enabled cycling computer. I put a GPS computer on my wish-list for this holiday season, and I'm hoping for the
Garmin 310, which is actually a GPS watch which I intend to use for running as well as cycling. It's tiny and can't display maps, but I don't care about that, I really just want the tracking and basic stats.