I have to pick 5? I couldn't narrow down 5 sports that I am watching this weekend let alone all year. I'll try in no particular order....
Rugby: Bledisloe Cup New Zealand vs Australia
Any sporting rivary between NZ and Aust is legendary but the Bledisloe cup is by far the best. The World Cup may come around only every four years but for all round brutality and bragging rights you can't go past the Bledisloe cup. I felt so cheated when for a few years they reduced it to best of 2 Tests but now they have rightly reversed it to at least 3 matches with an extra one usually hosted in Hong Kong or Tokyo.
Rugby League State of Origin NSW vs Qld
State vs State, mate vs mate. Think of an All Stars game but instead of an airy fairy giggle fest of high scoring entertainment you have extreme hate and violence between usually club team mates. You play for the team where you are born and for the week leading up to each of the three matches each season the whole state is on edge. You will get a player smashing his opponent one night and the playing beside him a couple of days later. Add to this the fact that the matches are played on a Wednesday night between club matches, and depending where the match is being played no one in Brisbane or Sydney works very hard. Half the city is usually still drunk the next day.
Motorsport: Isle of Man TT
Close call between this and the Monaco F1, but the fact the Monaco track is impossible to pass on and you rarely have any real racing gives the nod to the TT. Racing around wild street circuit on an Island with nothing but hay bails often protecting the rider from stone buildings and street curbs. Honorable mention goes to the Le Mans 24hr.
Test Match Cricket, Day 1 Brisbane
I'll watch any Test cricket regardless of the teams. You can't beat the rivaries between India and Pakistan or the antient battle for the Ashes between Australia and England. 5 long days of physical and mental battles with a wearing pitch and the chance that no winner can be decided at the end. Boxing day is all about the start of the Melbourne Test which is a great excuse to sit in front of the tele and drink beer while eating xmas left overs but personally the first day in Brisbane is my favourite. It is usually the first home Test of the Summer in Australia and half of Brisbane can be found either in the stands with a beer right before the first ball is bowled at 9.30am or across the road drinking steins at the Brisbane German Club during the Lunch and Tea breaks. le sigh
Golf: British Open
The home of golf, esecially when it is played on any number of wind swept links courses. Best part is you never have to hear the crass, drunk Americans screaming "In the hole" like a bunch of savages.
Olympics: Winter
I love many of the tradtional events of the Summer Olympics such as the 100m, Pentathlon, the rowing 8's, and the cycling teams pursuit, but there is something about the Winter Olympics that I love more. Perhaps it is the danger factor of almost every event on snow and ice that appeals
Soccer: World Cup Final
I loved waking up in the middle of the night and watching the FA cup final when was a kid, or watching the Champions League over a long and hard fought season but the pinnicle for me is every four years watching the World Cup. The best players for the biggest prize.
Tennis: The French Open
Wimbeldon may have the grass and the stawberries and cream but Roland Garros has the clay and the beautiful people. Many players and dominate for an entire career yet never crack the clay surface. Pretty girls sitting in the stands may also sway me.