I'd pick Chelsea for fourth. My logic is this: Even if Chelsea finish fifth, they do have some class players in their team and have the reputation to attract top players as well. If Roman goes into overdrive, which I suspect he will, they'll be back into it in no time, despite the season without Champions League.
Spurs, on the other hand, can become a dangerous outfit, with the addition of a couple of good players and they'll spend for sure if they are in the Champions League again. However, if they don't qualify, it will be very hard for them to retain their good players or get stronger players in to get back into the top four fold. Basically, they'll be out of it. for good and I'll definitely prefer that.