I have used
SportTracks for years (back when it was a PC app) but signed up for Training Peaks last November. I decided to try and get more serious with my training and try to plan more and everyone else seemed to be on Training Peaks and many plans were tied in to TP. But I agree the interface isn't great and some things just seem overly complicated.
I'm now looking at 4 apps to analyze my performance/training and each one has something another doesn't have or presents the data in a more readable way. I don't have a coach or use a purchased plan as I like to be more flexible with my exercise. I'm a middle to back of pack retired 63 year old that does 2-3 70.3's a year. I'm interested in sports science and still think I can get faster, but I'm not obsessed with it. I think I will end up giving up on Training Peaks and concentrate on SportTracks for planning and some reporting and use Garmin and Strava for more specific reporting.
Training Peaks is more customisable for setting zones and they are fine tunable and the reporting of peak performances is nice. But it's just so overwhelming the levels of detail it's trying to present, you can't see the wood for the trees.
SportTracks is more adaptable to smaller screen sizes, it's easy to create workouts from existing activities, but the reports are a bit more limited in some areas. Swim data is handled well. The biggest problem is that there isn't much in the way of help, you need to trawl through blog posts to find out how stuff works. But I think I prefer it to Training Peaks now I have spent time to try and understand it more. I like that it's not a phone app, just works in any browser, any device, one interface across all platforms.
Garmin Connect is a mess, the navigation and presentation is jumbled and inconsistent. Swim data is handled well. Power data from my Assioma pedals is really good. But it's Training Status and Training Effect report is useless because it doesn't merge data from different devices. I use a Garmin Edge 530 on my bike and a Forerunner 935 watch for running, swimming and activity monitor. So my Edge training load doesn't take into account what I've done running with my watch, so both often end up reporting I'm not doing enough. But in other areas the integration with multiple devices like scales and constant heart rate and sleep monitoring and other health type reports makes life easy. It's a brilliant data collector and it can pass that data on to other services, like SportTracks and Strava.
Strava is best at comparing performance over segments or whole rides and the social bit of competition with friends. It's easy to look at year or month to date targets/challenges. But it doesn't have the planned workouts that would predicted fitness, fatigue and form. Analyzing the data in the
VeloViewer web app is interesting. Planning a ride route works well and combine with the web app
Headwind for help in choosing which direction for a loop ride. So not really a training aid, more of a data analysis tool.