I wouldn't touch either with a 10 foot pole. They don't fill needs on this team.
Lopez is a sieve on defense who has been oft injured and carries one of the worst contracts in the league. He provides scoring, but not much else. We already have big men who can stretch the floor. Why do we need another? Lopez does not fill a need. Plus, he's not opting out of his $16m this year.
Monte Ellis is an undersized SG who is known as a chucker. His EFG is LOWER than Avery Bradley and he brings significantly less on the defensive side of the ball. He's a significantly better facilitator (he doesn't get enough credit for his passing), but he's also going to be more expensive and will be 30 shortly after the season starts. Defensively, you can't put him on the court with IT unless you want to give up 120 points a game. Finally at age 30, by the time this group of youngsters is ready to contend (if ever), he'll be washed up and long gone. So where's the benefit?
Someone might claim that these guys are upgrades, but they're marginal upgrades and significantly more expensive ones. To add Lopez and Ellis you are looking at close to $30m on the cap. That's nowhere near the bang for the buck that this team needs. Seriously, you would be hard pressed to pick two worse candidates to be on this team in terms of contribution, salary, age, fit on this team and replacement value.