I like Strava performance stats & Challenge awards.
Garmin environment & total stats,
Runkeeper has good goal setting,
and Map My Ride has other goals and awards.

I really wish I could have them all merged into one site.
Stats are awesome.

Strava Year-to-Date
Distance 1,192.4mi
Time 109hr 46m
Elev Gain 30,643ft
Rides 81

All-Time
Distance 1,192.4mi
Rides 81
Biggest Ride 60.2mi
Biggest Climb 33ft (WHAT!?!?!)

Bikes
Fens 4.0mi
Genesis 574.2mi
Paver 614.1mi

Garmin:
Count: 83 Activities
Distance: 1,179.91 mi
Time: 120:50:23 h:m:s
Elevation Gain: 44,072 ft
Avg Speed: 9.8 mph
Avg HR: 139 bpm
Avg Run Cadence: —
Avg Bike Cadence: 71 rpm
Calories: 65,550 C

Personal Records:
Elevation Gain 2185 ft 2013-09-28 TXF & HVP 2013/09/28
Longest Ride 60.2 mi 2013-09-28 TXF & HVP 2013/09/28