Training peaks probably is more in-depth than strava, considering the same people wrote WKO+ which is arguably the gold standard in anaylsys. Strava will show you that power graph, which is very important, as well as calculate TSS and IF and graphs your fitness/freshness chart. 99% of the time that's all the info I ever need, and the other 1% of the time I'd go into WKO+ (or potentially training peaks if I paid for that service, which I don't).

If you're getting started, buy the racing/training with a power meter book and use strava premium for all your tracking.