My Opinion Only (Been Riding Bikes all my life and now I'm in my late forties.........
696 Monster - Nice bike but parts very expensive as is servicing, bit of an old thumper of an engine, I think you'd get bored of it when your mate opened up his triumph you'll be out ridden in every way.
ER6-N - Great bike, with modern styling and engineering. You'd love it, it's light, agile and quick.
XJ6 - Heavy, but a lot of bike for the money. Personally if you rode an ER6 or a Triumph after purchasing an XJ6, you'd realize what a mistake you'd made. Good reliable bike though.
Gladius - Seen Them, Never Ridden One........ But compared with a Triumph Street Triple or Kawasaki ER6, it's not in the same league and doesn't have the same build quality. Still using a steel frame I believe.
Triumph - Well, there's no arguing the fact that it's won so many magazine shoot outs by a mile, just buy any bike mag and it will always be their top choice of for a 600 naked...... But as a result of this, they hold their money and are a little more expensive to buy, But you won't suffer from the same depreciation as most, so you get your money back when you decide you want a 1000cc bike (And You Will), but don't make the mistake of going for a 1000cc as your fist bike.......... Huge Mistake, which some people make. You need a minimum of a year of gaining experience on a good 600 before going to a 1 litre bike. 1000cc bikes in inexperienced hands is an accident waiting to happen.
Triumph would be my first choice, Kawasaki ER6 would be second choice.
Good Luck
