It's simple.
Presuming we don't bring in a left sided player before the start of the season who would you play on the left side against Spurs, presuming we go 4-2-3-1?
Lets not kid ourselves into thinking that Babel will start unless there are a bout of injuries. Basically, Kuyt will playon the right if fit and it's a straight fight between Riera and Benayoun for the other spot.
If you look at the two of them their seasons last year were almost the exact opposite. Riera came in and started like a house on fire but then faded towards the second half of the season. Benayoun on the other hand had a storming second half of the season, turning in some brilliant performances and scoring some vital goals.
Obviously they both have their strengths and weaknesses. Riera probably has better ball retention and will keep his shape better but can be easily marked out of games. He will however do more work defensively than Benayoun and for this reason you could probably argue that he'd be more suited to a tough away game at Tottenham.
Benayoun on the other hand is not a traditional wide player and is a lot more unpredictable than Riera but that gives you an advantage in that he's always capable of unlocking a defence or scoring. All in all he's probably more of an attacking threat than Riera. I wouldn't want to be Insua behind him though, especially with Aaron Lennon bombing down that wing all day. With our general lack of ability to break teams down at home last year who sat deep and defended you can probably see him starting more games at home than away.
So which of the two would you play away at Spurs and what do you think Rafa will do? Also, which of the two do you expect to have a bigger impact this season?