Man United and Spurs have the same number of goals conceded since the previous 5 matches. In terms of the number of scores obtained, Spurs are far superior because they managed to score 9 goals compared to MU only scoring 5 goals.
This means that both teams have a great chance of scoring and ending in a draw.
So I agree with your opinion to avoid betting on one team's victory. But, the BTTS odds are only @1.4+ and are not too tempting.
For me it would be more interesting to bet on over 3.5 with odds @2.07.
I doubt about TO 3.5, if teams concede on average one goal per match, you shouldn't expect anything to change in this match. I'm more inclined to think that the match will be something like the match with Arsenal, when a lot of attention will be paid to defense and the teams will be when the opponent makes a mistake. So I expect that there won't be many goals in this match, maybe even a goalless draw. Manchester United are too weak to win, but they don't want to lose either.